Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COMPRESSING AND RESTORING METHOD OF IMAGE DATA
Technical Field
This application is a division of Canadian Patent
Application Serial No. 2,394,545, filed December 20, 2000.
In view of division enforced by the Canadian Intellectual
Property Office, the claims of this application are
directed to image data compressing and restoring methods.
However, for the purpose of facilitating an understanding
of all objects and features of the development which are
inextricably bound-up in one and the same inventive concept
as taught and claimed in the parent Canadian Application
Serial No. 2,394,545 are retained herein.
Accordingly, in view of enforced division required by
the Examiner in the prosecution of the aforesaid patent
application, object clauses and features have been retained
for the purposes of facilitating and understanding of the
overall development. However, the retention of any clauses
or features which may be more particularly related to the
parent application or a separate divisional thereof should
not be regarded as rendering the teachings and claiming
ambiguous or inconsistent with the subject matter defined
in the claims of the divisional application presented
herein when seeking to interpret the scope thereof and the
basis in this disclosure for the claims recited herein.
Background of the Invention
In order to effectively utilize resources used for
processing image data, compressing and restoring methods of
image data are widely used.
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As one of the compressing and restoring methods of
image data, a method is known in which all the image
elements included in image data are compressed and restored
on the basis of one algorithm. In the conventional method
of compressing and restoring image data, image data
including various kinds of image elements, such as types,
handwritten characters, handwritten drawings, free micro
dots, tables, illustrations, graphics, tints and
photographs are compressed and restored on the basis of the
one algorithm.
However, the conventional method of compressing and
restoring the image data is difficult to suppress
deterioration in a picture quality caused by the
compression of the image data for all the image elements
included in the image data. For example, when an algorithm
which suppresses deterioration of the picture quality in
compressing and restoring an image data generated from a
photograph is used to compress and restore other image data
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generated from characters and lines, the edges of the
characters and the lines are not clearly restored.
Conversely, when another algorithm which suppresses
deterioration of the picture quality in compressing and
restoring image data generated from characters and lines
is used to compress and restore the image data generated
from photographs, the image of the photograph tend to be
distorted.
A compressing and restoring method of the image data
is desirably designed so as to suppress the deterioration
in the picture quality caused by the compression of the
image data.
Moreover, the conventional method of compressing and
restoring the image data is difficult to attain both the
improvement of a compression rate and the suppression of
the deterioration in the image data caused by the
compression of the image data with respect to all the image
elements. If image data generated from the image elements
such as types, handwritten characters, handwritten
drawings, tables and illustrations is compressed and
restored on the basis of the algorithm effective for image
data generated from photographs, edges of the image
elements are disgracefully restored. Furthermore, a
focus of the restored picture becomes loose. On the other
hand, use of an effective method for compressing the line
pictures and the like deteriorates the picture qualities
of graphics, tints, photographs and the like. Moreover,
a data amount of the compressed data is increased.
The compressing and restoring method of the image
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data is desirably designed to increase the compression
rate and to suppress deterioration of the picture quality
caused by the compression of the image data.
Also, operations of compressing and restoring image
data generated from pictures drawn on printed matters are
generally carried out. As shown in Fig. 41A, a picture
drawn on a colored printed matter is provided with pixels
501. Each of the pixels 501 is composed of a blue dot 502a,
a red dot 502b, a yellow dot 502c and a black dot 502d.
The blue dot 502a is a dot provided by a blue screen (a
C screen). The red dot 502b is a dot provided by a red
screen (an M screen ). The yellow dot 502c is a dot provided
by a yellow screen (a Y screen). The black dot 502d is
a dot provided by a black component (a K screen). The
arrangement of the blue dot 502a, the red dot 502b, the
yellow dot 502c and the black dot 502d is not limited to
that shown in Fig. 41. The blue dot 502a, the red dot 502b,
the yellow dot 502c and the black dot 502d are collectively
referred to as a dot 502. The dot 502 may be square-as
shown in Fig. 42(a), and may be differently shaped, for
example, circular as shown in Fig. 42(b).
The dots 502 included in one screen are regularly
arranged on screen lines 503 in accordance with a print
rule, as shown in Fig. 43. The screen lines 503 and an
X-axis cross each other at an angle defined by the print
rule. The angle is different for each of the screens. The
screen lines 503 are arranged in parallel to each other
at an equal interval. A screen ruling is defined as being
1/ds, where ds is the interval between the screen lines
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503. When a-line segment of a unit length, typically one
inch, in a direction vertical to the screen line 503 is
considered, the screen ruling implies the number of the
screen lines 503 crossing the line segment.
The dot 502 is arranged such that the center thereof
is located on the screen line 503. Here, when the dot 502
is square, the center of the dot 502 implies a point at
which the diagonals thereof cross each other. When the
dot 502 is formed in a circle, the center of the dot 502
lo implies a center of the circle.
An area of each dot 502 indicates a graduation. As
the area of the dot 502 is larger, an eye of a human
recognizes that a concentration of a position of the dot
502 is higher.
The picture composed of the dots having the
arrangements and the shapes as mentioned above originally
has a large redundancy.
However, the conventional method of compressing and
restoring the image data does not use the mechanism that
the picture drawn on the printed matter is composed of the
dots. The conventional method of compressing and
restoring the image data does not compress the picture
drawn on the printed effectively.
It is desired to provide a method of effectively
compressing the image data generated from the picture
composed of the dots and restoring it.
Moreover, in the conventional method of compressing
and restoring image data, the dot is compressed and
restored without any discrimination from other image
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elements included in the picture. The dot itself is not
restored. Here, if the restored image data is enlarged
or contracted, an area ratio of the dot to the entire
picture, namely, a dot percent is not stored. For this
reason, if the restored image data is enlarged or
contracted, a color may be deteriorated. Moreover, if the
restored image data is enlarged or contracted, moire may
be induced.
It is desired that the deterioration in. the picture
quality is not induced even if the operation such as the
enlargement or the contraction is performed on the
restored image data while the image data generated from
the picture composed of the dots is compressed and
restored.
Also, in the image data compressing method, the
compression of image data is desired to be executed at a
high speed. In particular, the compression of image data
indicative of a picture whose edge is emphasized is desired
to be done at a high speed.
Also, in the image data compressing method, it is
desired to provide a compressing and restoring method of
image data, which effectively compresses and restores
image data generated from a printed matter composed of
micro point, each of which does not have the arrangements
defined by the print rule and has small areas.
Summary of the Invention
An object of the present invention is to provide a
compressing and restoring method of image data, in which
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deterioration in picture qualities caused by the
compression and restoration is suppressed.
Another object of the present invention is to provide
a compressing and restoring method of image data, in which
a compression rate is large.
Still another object of the present invention is to
provide a compressing and restoring method of image data,
in which a compression rate is large and deterioration in
picture qualities caused by the compression and
restoration is suppressed.
Still another object of the present invention is to
provide a compressing and restoring method of image data,
in which image data generated from a printed matter
composed of dots is effectively compressed and restored.
Still another object of the present invention is to
provide a compressing method of image data, in which the
compression of the image data is done at a high speed.
Still another object of the present invention is to
provide a compressing method of, image data, in which the
compression of image data representative of pictures whose
edges are emphasized is done at a high speed.
Also, it is to provide a compressing and restoring
method of image data, in which image data generated from
a printed matter composed of micro points, each of which
does not have the arrangement defined by the print rule
and has a small area is effectively compressed and
restored.
According to the invention, there is pro-
vided an image data compressing method comprising the
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steps of: extracting image elements included in a digital
image obtained from a paper surface, performing data
compression on each of the image elements extracted by
compressing methods corresponding to the image elements, and
storing each of the image element data in compressed form in
a memory, wherein when the image elements extracted include
a dot image element composed of dots, the image element data
in compressed form associated with the dot image element is
generated so that the image element data in compressed form
comprises: position information corresponding to positions
of the dots and screen ruling information corresponding to an
arrangement of the dots.
The respective images have respective features.
The respective image elements can be classified and
extracted on the basis of the features. The compression
and restoration of the image element data in accordance
with algorithms corresponding to kinds of the extracted
image elements enable to suppress the deterioration in the
picture quality caused by the compression and restoration.
Also, they result in the improvement of a compression rate.
For example, the compressing and restoring processes
effective for edges are performed on an image whose edges
are desired to be clearly restored. The compressing and
restoring processes effective for a print dot picture are
performed on the image such as.graphics, tints and
photographs, in which print pictures are desired to be
clearly restored. The compressing and restoring
processes effective for a set of fine micro points arranged
without any rules (hereinafter, they may be referred to
as "free micro dots") are carried out in order to restore
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a set of free micro dots at a high compression and a clear
manner.
As a method of judging a kind of each image element,
the following judging methods can be used.
In a first judging method, the kind of each image
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element is judged by the processes in the following. An
image element constituted by a set of the free micro dots
is distinguished by the fact that the areas thereof are
larger than print dots and smaller than a predetermined
area, and.the image element does not have regularity of
the print dots. Also, the print picture is a set of the
small dots having the regularity of the print dots. The
print picture is distinguished by the existence of the
regularity of the print dots. A11 the remaining image
elements are judged as line picture images.
In a second judging method, the kind of each image
element is distinguished by a difference of a form element.
A type character has a feature of a character appearance.
A handwritten character has no feature of the character
appearance. Also, a signet, a seal and a line picture have
a feature of a set of free lines, namely, a feature that
there is neither character appearance nor print dot. A
tint has a feature that there is a regularity of print dots
and there is no graduation. A graduation net has a feature
that there is the regularity of the print dots and there
is a graduation in dot rows. A photograph net has a feature
that although there is the regularity of the print dots,
there is no regularity in the tint and the graduation net.
The kind of each image element is judged from those
features.
In a third judging method, the kind of each image
element is distinguished by a difference of a display
element. In short , sentences have a feature that a series
of characters are continuously arranged. Comics have a
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feature that -there are an illustration, a free micro line
and a micro dot. Also, maps have a feature that there is
a determined regularity with regard to a map.
Advertisements have a feature that there is an
advertisement frame and there is regularity with regard
to an arrangement on a page space. Tables have a feature
that there is a quadrangle composed of ruled lines.
Photographs have a feature that there is no regularity in
the tint and the graduation net while there is the
regularity of the print dots. The kind of each image
element is judged from those features.
In the image data compressing method, each
compressed image element data is desirably provided with
a position information representative of where the image
element corresponding to each image element data existed
on the page space, and a screen ruling information.
Also, in the image data compressing method, the
digital image obtained from the page space may be a color
image. In this case, the extraction of the image element
and the data compression of the image element are desired
to be carried out for each color component.
According to the invention, there is pro-
vided an image data restoring method comprising
the steps of: restoring compressed image element data
associated with image elements by using restoring methods
corresponding to the image elements, and superimposing and
synthesizing the image elements restored to thereby restore
an image, wherein when the compressed image element data
include dot compressed image element data associated with a
dot image element comprising dots, effecting an editing
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process using position information and screen ruling
information contained in the compressed image element data
associated with the dot image element, said position
information corresponding to positions of the dots, and
screen ruling information of screen ruling according to which
said dots are arranged corresponding to an arrangement of the
dots.
In this case, a position information and a line
density information added to each compressed image element
data are used to carry out an editing process, such as a
rotation, a variation, an enlargement or a contraction of
the image element, and then restore the page space image.
Also, the compressed image element data is provided
for each color component. In this case, preferably, an
image element data for each color component is restored
by using a restoring method corresponding to a kind of the
image element, and the restored image element for each
color component is superimposed and synthesized to thereby
restore an image.
According to the invention, there is pro-
vided an image data compressing method comprising
the steps of: obtaining an image data representative of a
picture; extracting a first image element data from the image
data; extracting a second image element data from the image
data; compressing the first image element data to generate a
first compression image element data and compressing the
second image element data to generate a second compression
image element data, wherein a first extracting algorithm for
extracting the first image element data is different from a
second detracting algorithm for extracting the second image
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element data, a first compressing algorithm for generating
the first compression image element data is different from a
second compressing algorithm for extracting the second image
element data, wherein, when the first and second image
elements data include a dot image element composed of dots,
the corresponding first and second compression image element
data associated with the dot image element is generated so
that the first and second compression image element data
comprises: position information corresponding to positions
of the dots, and screen ruling information corresponding to
an arrangement of the dots.
The first and second element data, which are
extracted from the first and second extracting algorithms
that are different from each other, have the features
different from each other. The first and second image
element data, which have the features different from each
other, are respectively compressed in accordance with the
first and second compressing algorithms that are different
from each other. This enables to suppress the
2o deterioration in the picture quality caused by the
compression and the restoration, and also results in the
improvement of the compression rate.
It should be noted that another image element data
other than the first and second image element data might
be extracted from the image data by using another
extracting algorithm. In this case, the other image
element data is compressed by using another compressing
algorithm to generate another compression image element
data.
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In the image data compressing method, the obtaining
step preferably includes the steps of:
obtaining a color image data representative of a
color picture; and
extracting a portion representative of a component
of a predetermined color from the color image data to
generate the above-mentioned image data.
This provides the compressing and restoring method of
the color image data in which the deterioration in the
picture quality is suppressed. Also, this provides the
compressing and restoring method of the color image data in
which the compression rate is improved.
This provides the compressing and restoring method of
the color image data in which the deterioration in the
picture quality is suppressed. Also, this provides the
compressing and restoring method of the color image data in
which the compression rate is improved.
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Also, in the image data compressing method, the step
of extracting the first image element data preferably
includes the step of extracting a first portion from the
image data to generate the first image element data. The
first portion corresponds to a dot portion composed of dots
in the picture.
In this case, the step of generating the first
compression image element data preferably includes the
step of generating the first compression image element
data on the basis of the areas of the dots.
In the image data compressing method, the step of
extracting the second image element data preferably
includes the step of extracting a second portion from the
image data to generate the second image element data. The
second portion corresponds to a free micro dot region of
the picture, the free micro dot region including free micro
dots which are not the above-mentioned dots and each of
which has an area equal to or less than a predetermined
area.
Also, the step of generating the second compression
image element data preferably includes the steps of:
dividing the free micro dot region into a plurality
of rectangular regions;
recognizing a shape of a pattern inside each of the
rectangular regions, the pattern being included by image
patterns of the image; and
encoding the shape to generate the second
compression image element data.
Also, the free micro dots may include first and
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second free micro dots. In this case, the step of
generating the second compression image element data
preferably includes the step of generating the second
compression image element data, on the basis of a relative
position between the first free micro dot and the second
free micro dot.
Also, the step of generating the second compression
image element data preferably includes the steps of:
defining a rectangular region including free micro
dots in the free micro dot region; and
generating the second compression image element data
on the basis of in accordance with an aver-age of
concentrations inside the rectangular region.
Preferably, the image data compressing method
further includes the step of extracting a third image
element data that is a portion of the image data other than
the first image element data and the second image data of
the image data.
Preferably, the image data compressing method
further includes the step of generating a collectively
compressed image element data on the basis of the first
compression image element data and the second compression
- image element data.
In the image data compressing method, the step of
generating the first compression image element data
preferably includes the steps of:
detecting a graduation of an image element
represented by the first compression image element data
by scanning along a scanning line;
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calculating an outline position of an outline of the image
element on the basis of the graduation; and generating the
first compression image element data in accordance with the
boundary position.
According to an aspect of the present invention, there
is provided a computer-implemented method for compressing
image data, comprising the steps of obtaining an image data
representative of a picture including dots, wherein the
dots comprise first and second dots; calculating areas of
the dots, wherein the areas includes a first area of the
first dot and a second area of the second dot; calculating
positions of the dots, wherein the positions include a
first position of the first dot and a second position of
the second dot; and generating a compression data based on
an area difference between the first area and the second
area and a distance between the first position and the
second position.
In the image data compressing method, the step of
obtaining the image data representative of the image
including the dots preferably includes the steps of
obtaining another image data representative of another
picture; and generating the above-mentioned dots based on
graduations of the other picture to generate the image
data.
According to a second aspect of the present invention,
there is provided a computer-implemented method for
compressing image data, comprising the steps of obtaining
an image data representative of a line picture; detecting
graduations of the line picture while scanning along a
scanning line; calculating edges of the line picture based
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on the graduations; defining outline vectors by linking the
edges; and generating a compression data based on the
outline vectors.
According to a third aspect of the present invention,
there is provided a computer-implemented method for
comprising image data, comprising the steps of obtaining an
image data representative of a picture including free micro
dots having an area within a predetermined area range,
wherein the free micro dots include first and second micro
dots; and generating a compression data based on positions
of the free micro dots wherein the generating said
compression data includes generating the compression data
based on a relative position between the first free micro
dot and the second free micro dot.
Also, the step of generating the compression data
preferably includes the steps of defining a rectangular
region containing the free micro dots in the picture; and
generating the compression data on the basis of an average
of concentrations inside the rectangular region.
It is also preferable that it further includes the
steps of defining a rectangular region containing the free
micro dots in the picture; and generating the compression
data on the basis of a distance between the free micro dots
and a side of the rectangular region.
Also, the step of generating the compression data
preferably includes the steps of defining a rectangular
region in the picture; recognizing a shape of a pattern of
a portion included in the rectangular region in the free
micro dots; and encoding the shape and generating the
compression data.
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According to a fourth aspect of the present invention,
there is provided a computer-implemented method for
extracting image data, comprising the steps of obtaining an
image data representative of a picture containing a dot;
and extracting a portion representative of the dot from the
image data.
In this case, the extracting step preferably includes
the steps of scanning the picture to detect a change
position at which a graduation is changed; and extracting
the portion on the basis of an interval between the change
positions.
According to a fifth aspect of the present invention,
there is provided a computer-implemented method for
processing image data, comprising the steps of obtaining an
image data representative of a picture including first and
second dots having an arrangement in accordance with a
print rule; shifting the second dot to define a virtual
dot, wherein a virtual dot position of the virtual dot is
located on a straight line which passes the first dot and
the second dot, the virtual dot is located in a first
direction orienting to the second dot from the first dot
with respect to the second dot, and a virtual dot area of
the virtual dot is equal to a second dot area of the second
dot; generating another third dot located between the first
dot and the virtual dot on the straight line, wherein a
third dot position of the third dot is determined so as to
comply with the print rule, and a third dot area of the
third dot is determined by an interpolation from a virtual
dot position of the virtual dot, a dot position of the
first dot, the third dot position, a first dot area of the
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first dot, and the virtual dot area; and erasing the
virtual dot.
Here, a virtual dot position of the virtual dot is
located on a straight line through which the first dot and
the second dot are connected. Moreover, the virtual dot is
located in a first direction toward the second dot from the
first dot with respect to the second dot. A virtual dot
area of the virtual dot is equal to a second dot area of
the second dot. A third dot position of the third dot is
determined so as to comply with the print rule. A third
dot area of the third dot is determined by an interpolation
on the basis of a virtual dot position of the virtual dot,
a dot position of the first dot, and the third dot position
of the third dot, a first dot area of the first dot and the
virtual dot area of the virtual dot.
According to the invention, there is provided an image
data restoring method comprising the steps of obtaining
compression data, wherein the compression data comprises a
first compression image element data compressed in
accordance with a first compressing algorithm; and a second
compression image element data compressed in accordance
with a second algorithm which is different from the first
compressing algorithm, restoring the first compression
image element data to generate a first restoration image
element data; restoring the second compression image
element data and to generate a second restoration image
element data; and generating one image data from the first
restoration image element data and the second restoration
image element data, whereby, when the first and second
compression image element data includes dot compressed
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image element data associated with a dot image element
comprising dots, effecting an editing process using
position information and screen ruling information
contained in the first and second compression image element
data associated with the dot image element, the position
information corresponding to positions of the dots.
According to a sixth aspect of the present invention,
there is provided a computer-implemented method for
restoring image data, comprising the steps of obtaining a
compression data including an area difference data
representative of the difference in the area between a
first dot and a second dot, and a distance data
representative of a distance between the first dot and the
second dot; and restoring an image data containing the
first dot and the second dot based on the area difference
data and the distance data.
In the image data restoring method, the image data is
restored so as to further include a third dot located
between the first dot and the second dot; and an area of
the third dot is determined on the basis of the area
difference data.
According to a seventh aspect of the present
invention, there is provided a computer-implemented method
for restoring image data, comprising the steps of obtaining
a compression data, wherein the compression data includes a
position data representative of a position of a free micro
dot having an area within a predetermined area range; and
restoring an image data representative of a picture
composed of the free micro dot based on the position.
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In this case, it is preferable that the compression
data includes an average of concentrations inside a
rectangular region defined for the picture, and the step of
restoring the image data includes the step of restoring the
image data on the basis of the average.
It is also preferable that the position data has a
distance between the free micro dot and a side of a
rectangular region defined for the picture, and the step of
restoring the image data includes the step of restoring the
image data on the basis of the distance.
According to the invention, there is provided a
recording medium for recording a program for effecting the
steps of obtaining an image data representative of a
picture; extracting a first image element data from the
image data; extracting a second image element data from the
image data; compressing the first image element data to
generate first compression image element data; and
compressing the second image element data to generate the
second compression image element data, wherein a first
extracting algorithm for extracting the first image element
data is different from a second extracting algorithm for
extracting the second image element data, and a first
compressing algorithm for generating the first compression
image element data is different from a second compressing
algorithm for extracting the second compression image
element data, whereby, when the first and second image
elements data include a dot image element composed of dots
and the corresponding first and second compression image
element data associated with the dot image element is
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generated so that the first and second compression image
element data comprises position information corresponding
to positions of the dots, and screen ruling information
corresponding to an arrangement of the dots.
According to an eighth aspect of the present
invention, there is provided a computer readable memory
having recorded thereon statements and instructions for
execution by a computer to carry out a method for
compressing image data, comprising the steps of obtaining
an image data representative of a picture including dots,
wherein the dots comprise first and second dots;
calculating areas of the dots, wherein the areas includes a
first area of the first dot and a second area of the second
dot; calculating positions of the dots, wherein the
positions include a first position of the first dot and a
second position of the second dot; and generating a
compression data based on an area difference between the
first area and the second area and a distance between the
first position and the second position.
According to a ninth aspect of the present invention,
there is provided a computer readable memory having
recorded thereon statements and instructions for execution
by a computer to carry out a method for comprising image
data, comprising the steps of obtaining an image data
representative of a picture including free micro dots
having an area within a predetermined area range, wherein
the free micro dots include first and second micro dots;
and generating a compression data based on positions of the
free micro dots, wherein the generating the compression
data includes generating the compression data based on a
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relative position between the first free micro dot and the
second free micro dot.
According to a tenth aspect of the present invention,
there is provided a computer readable memory having
recorded thereon statements and instructions for execution
by a computer to carry out a method for compressing image
data, comprising the steps of obtaining an image data
representative of a line picture; detecting graduations of
said line picture while scanning along a scanning line;
calculating edges of said line picture based on said
graduations; defining outline vectors by linking said
edges; and generating a compression data based on said
outline vectors.
According to an eleventh aspect of the present
invention, there is provided a computer readable memory
having recorded thereon statements and instructions for
execution by a computer to carry out a method for restoring
image data, comprising the steps of obtaining a compression
data including an area difference data representative of
the difference in the area between a first dot and a second
dot, and a distance data representative of a distance
between the first dot and the second dot; and restoring an
image data containing the first dot and the second dot
based on the area difference data and the distance data.
Brief Description of Drawings
Fig. 1 is a flowchart showing an image data
compressing method of a first embodiment of the present
invention;
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Fig. 2 shows a hardware resource 10 in which the image
data compressing method of the first embodiment and a
restoring method are carried out;
Fig. 3 shows an image 30 to be compressed;
Fig. 4 shows an image element included in a free micro
dot image element data 51;
Fig. 5 shows an image element included in a print dot
image element data 52;
Fig. 6 shows an image element included in a line
lo picture image element data 53;
Fig. 7 is a view describing a free micro dot pattern
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compressing algorithm;
Fig. 8 is a view showing various patterns of an area
patch 71;
Fig. 9 shows a part of a picture included in the print
dot image element data 52;
Fig. 10 is a flowchart showing a print dot pattern
compressing algorithm;
Fig. 11 is a.view showing a first method of
calculating an area of a dot and a method of determining
a center of the dot;
Fig. 12 is a view showing a second method of
calculating an area of a dot;
Fig. 13 is a view showing a first method of extracting
screen lines;
Fig. 14 is a view showing a second method of
extracting screen lines;
Fig. 15 is a view showing possible arrangements in
dots 811 to 814;
Fig. 16 is a view showing a third method of extracting
screen lines;
Fig. 17 is a view showing a method of calculating
a screen angle;
Fig. 18 is a view showing a method of calculating
a screen ruling;
Fig. 19 is a view showing a method of calculating
a dot vector;
Fig. 20 is a view showing positions at which a dot
1010 and dots 10111 to 1011n are located in an imaginary
coordinate system Q1;
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Fig. 21 =shows a picture to be compressed on the basis
of a line picture compression algorithm;
Fig. 22 shows a detecting method of edges 112;
Fig. 23 shows the edges 112;
Fig. 24 shows a detecting method of a noise;
Fig. 25 shows outline vectors 1151 to 1158;
Fig. 26 shows a process of smoothing an outline;
Fig. 27 shows a process of smoothing the outline;
Fig. 28 is a flowchart showing the image data
restoring method of the first embodiment of the present
invention;
Fig. 29 is a flowchart showing a print dot restoring
algorithm;
Fig. 30 is a flowchart showing a process for
restoring dots;
Fig. 31 is a flowchart showing a line picture
restoring algorithm;
Fig. 32 is a flowchart showing a process for
compressing a color page space image data representative
of a color picture;
Fig. 33 shows a process in which a picture consists
of print dots is simultaneously enlarged while print dot
compression data module is restored;
Fig. 34 shows process in which a picture consists
of print dots is simultaneously contracted while print dot
compression data module is restored;
Fig. 35 shows a process in which a restored picture
is simultaneously contracted while a line picture
compression data module 56 is restored,
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Fig. 36 'shows a process in which a restored picture
is simultaneously enlarged while the line picture
compression data module 56 is restored;
Fig. 37 shows a free micro dot vector compressing
algorithm;
Fig. 38 shows a hardware resource 10' in which an
image data compressing method of a second embodiment is
carried out;
Fig. 39 is a flowchart showing the image data
10. compressing method of the second embodiment;
Fig. 40 is a flowdhart showing an image data
restoring method of the second embodiment;
Fig. 41 shows a structure of a pixel 501;
Fig. 42 shows a structure of a dot 502;
Fig. 43 shows a picture composed of dots;
Fig. 44 shows an extracting method of a set of dots;
and
Fig. 45 is a view describing a free micro dot data
compressing algorithm.
Detailed Description of the Invention
Embodiments according to the present invention will
be described below with reference to the attached
drawings.
(First Embodiment)
A compressing method and a restoring method of an
image data of the first embodiment is a method of
compressing and restoring an image data generated by
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capturing a picture drawn on a paper with a scanner.
The compressing and restoring method of the image
data of the first embodiment is carried out by using a
hardware resource. As shown in Fig. 2, the hardware
resource 10 includes a scanner 1, a CPU 2, a memory 3, a
recording medium 4 and a bus 5. The scanner 1, the CPU
2, the memory 3 and the recording medium 4 are connected
to the bus 5. The scanner 1 captures an image 30 drawn
on a page space to generate a page space image data 50.
The CPU 2 carries out an operation for compressing or
restoring the page space image data 50. The memory 3
stores the page space image data 50 and the data generated
by the process for carrying out the compressing and
restoring method of the image data of the first embodiment.
The recording medium 4 stores a program describing the
procedures included in the compressing and restoring
method of the image data of the first embodiment. The CPU
2 is operated in accordance with the program. The bus 5
transmits the data to be exchanged between the scanner 1,
the CPU 2, the memory 3 and the recording medium 4.
In the compressing method and the restoring method
of the image data of the first embodiment, at first, as
shown in Fig. 1, the image 30 drawn on the page space is
captured by the scanner 1 to generate the page space image
data 50 (Step SO1).
The image 30, which is captured by the scanner 1,
is a monochrome image. As shown in Fig. 3, the image 30
is provided with a title 31, main sentences 32, a
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photograph 33, a table 34, an illustration 35, a graphic
36, advertisement characters 37, a comic 38, and a
photograph title 39, which are randomly arranged. The
title 31, the main sentence 32 and the advertisement
characters 37 are constituted by characters printed with
type. The photograph 33 and the graphic 36 are constituted
by a group of dots having an arrangement defined by a print
rule.
Hereafter, an element constituting the image 30 may
be referred to an image element. Each of The title 31,
the main sentence 32, the photograph 33, the table 34, the
illustration 35, the graphic 36, the advertisement
characters 37, the comic 38 and the photograph title 39
constitutes an image element. Moreover, parts of the
title 31, the main sentence 32, the photograph 33, the
table 34, the illustration 35, the graphic 36, the
advertisement 37 and the comic 38 can constitute an image
element.
Next, the image elements of the image 30,which is
represented by the page space image data 50, are extracted
and classified (Step S02).
Portions corresponding to micro dots placed without
complying with the print rule are extracted from the page
space image data 50 to generate a free micro dot image
element data 51. Hereafter, the micro dots placed without
complying with the print rule is referred to as free micro
dots. Regions that are placed without complying with the
print rule are smaller than a predetermined area and larger
than an area of a print dot, are extracted as the free micro
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dots.
Fig. 4 shows a content of the free micro dot image
element data 51. As shown in Fig. 4, the free micro dot
image element data 51 is provided with the data indicative
of an image element 40 that is a part of the comic 38. That
is, the portion corresponding to the image element 40 is
extracted as the free micro dot image element data 51 from
the page space image data 50.
The free micro dot image element data 51 is
implemented with position information representative of
a position of the image element 40 included in the free
micro dot image element data 51.
Moreover, the portion corresponding to a group of
the dots included in the image 30 is extracted from the
page space image data 50 to generate a print dot image
element data 52 (Step S04). The group of dots has an
arrangement defined by the print rule. The group of the
dots is extracted by using the fact that the group of dots
has an arrangement defined by the print rule to generate
the print dot image element data 52.
First, a set composed of points having an area
smaller than a maximum area of a dot defined by the print
rule is extracted from the page space image data 50.
Moreover, it is judged whether or not the set is a set of
print dots. Fig. 44 shows a set 200 extracted from the
page space image data 50. The set 200 is composed of points
201.
The set 200 is scanned along a scanning line 202
extending in an X-axis direction. An edge of the point
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201 is detected from the change in a graduation. Let us
suppose that an edge 203a of a certain point 201a is
detected as the result of the scanning along the scanning
line 202. Moreover, let us suppose that the set 200 is
scanned along the scanning line 202 to sequentially detect
an edge 203b and an edge 203c located at left ends of other
points 201b, 201c, respectively. Moreover, in this case,
if a first interval between the edge 203a and the edge 203b
and a second interval between the edge 203b and the edge
203c are a predetermined unit interval, the point 201a,
the point 201b and the point 201c are judged to be the dots.
As for the other points 201, it is judged whether or not
their points are the dots in the same way. If most of the
points 201 included in the set 200 are judged to be the
----------------
dots, the set 200 is judged to be the set of the dots.
The above mentioned unit interval is determined on
the basis of a density of the screen lines 203 defined by
the print rule and a possible angle between the scanning
line 202 and the screen line 203. If the points 201
included in the set 200 are the dots, they must be arrayed
on the screen line 203. In this case, the angle between
the scanning line 202 extendingaiongthex-axis direction
and the screen line 203 is determined to be one of 0 , 15
, 45 , 60 , 75 and 90 in accordance with the print
25 rule. Moreover, an interval ds between the screen lines
203 is also determined in accordance with the print rule.
Six unit intervals dnorml to dnorm6 are respectively
determined corresponding to the six angles except 0 from
among the possible angles between the scanning line 202
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and the screen line 203. It holds
dnormi = ds cos 8s1,
where
8s1 = 15 ,
0g2 = 30 ,
s3 = 45
6$' = 60
855 = 750 , and
686 = 90
If an interval between any one point among the points 201
included in the set 200 and an edge of another point
adjacent thereto is substantially equal to one unit
interval among the six unit intervals dnorm' to dnormb = the
set 200 is judged to be the set of the dots.
If the angle between the scanning line 202 and the
screen line 203 is 0 , this method is impossible to judge
whether or not the certain set 200 is the set of the dots.
Changing the direction of the scanning line 202, however,
enables to judge whether or not the set 200 is the set of
the dots.
The set 200 judged to be the set of the dots is
extracted to thereby generate the print dot image element
data 52.
It should be noted that the direction of the scanning
line is not limited to the x-axis direction. Needless to
say, the. direction of the scanning line may be a different
direction.
Fig. 5 shows a content of the print dot image element
data.52 . As shown in Fig. 5, the print dot image element
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data 52 is composed of data representative of the
photograph 33 and the graphic 36. That is, the portion
corresponding to the photograph 33 and the graphic 36 is
extracted from the page space image data 50 as the print
dot image element data 52.
The print dot image element data 52 is implemented
with position information representative of the positions
of the graphic 36 and the photograph 33 included in the
print dot image element data 52.
Moreover, the portion that is not extracted as the
free micro dot image element data 51 nor as the print dot
image element data 52 is extracted as a line picture image
element data 53 (Step S05).
Fig. 6 shows a content of the line picture image
element data 53. As shown in Fig. 6, the line pictu.re image
element data 53 is constituted by data representative of
the title 31, the main sentences 32, the table 34, the
illustration 35, the advertisement characters 37, the
image element 40 and the image element 41 that is a part
of the comic 38. A portion of the image 30 that is poor
in change of contrast and corresponds to a portion whose
edge is clear is stored in the line picture image element
data 53.
As shown in Fig. 1, the above mentioned free micro
dot image element data 51 is compressed in accordance with
a free micro dot compressing algorithm to generate a free
micro dot compression data module 54 (Step S03) In the
free micro dot pattern compressing algorithm, an area to
be compressed is divided into area patches. Moreover, a
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pattern included in each of the area patches is encoded
to thereby generate the free micro dot compression data
module 54.
The free micro dot pattern compressing algorithm
will be described below in detail.
As shown in Fig. 7, a target area 70 to be compressed
is divided into area patches 71. Each of the area patches
71 is composed of 16 small regions 72 arranged in 4 rows
and 4 columns. The number of the small regions 72 included
in the area patch 71 is not limited to 16 (4 rows and 4
columns). For example, each of the area patches 71 may
be composed of 16 small regions arranged in 8 rows and 8
columns. -
Moreover, a pattern of each of the area patches 71
is recognized. The pattern is recognized on the basis of
whether or not an image element 73 exists in each of the
small regions 72 included in the area patch 71.
Fig. 8 shows the examples of various patterns of
the area patches 71. Fig. 8(a) shows an area patch 71
having a zero pattern. The area patch 71 has no image
element 73. Fig. 8 (b) shows an area patch 71 having a
lower right pattern. The lower right pattern is the
pattern where the image elements 73 exist in four small
regions 72 located in the lower right portion of the area
patch 71. Fig. 8 (c) shows an area patch 71 having a
central pattern. The central pattern is the pattern where
the image elements 73 exist in four small regions 72
located in the center of the area patch 71. Fig. 8 (d)
shows an area patch 71 having an upper right pattern. The
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upper right pattern is the pattern where the image elements
73 exist in two small regions 72 located in the upper right
portion of the area patch 71. Fig. 8 (e) shows an area
patch 71 having a right 1 pattern. The right '1- patter
is the pattern where the image element 73 exists in a small
region 72 located on a second line from the bottom of the
area patch 71 and on a first row from the right. Fig. 8
(f) shows an area patch 71 having a - right 1 pattern. The
- right 1 is the pattern where the image element 73 exists
in a small region 72 located on a second line from the bottom
and on a first row from the left.
In the free micro dot pattern compressing algorithm,
symbols different from each other are predetermined
corresponding to each of the various patterns of the area
patch 71. The symbols different from each other are
defined corresponding to each of the patterns shown in Figs.
8 (a) to (f).
The pattern of the area patch 71 is encoded with the
predetermined symbols. The encoded pattern is compressed,
and the free micro dot pattern compressing algorithm is
completed.
The free micro dot image element data 51 is
compressed in accordance with the above mentioned free
micro dot pattern compressing algorithm to thereby
generate the free micro dot compression data module 54.
On the other hand, as shown in Fig. 1, the print dot
image element data 52 is compressed in accordance with the
print dot compressing algorithm to generate a print dot
compression data module 55 (Step S04). The print dot
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compressing algorithm calculates a direction of the screen
lines on which the dots are arrayed, and a screen ruling
of the screen lines per unit length. Moreover, a dot
vector having as the elements thereof the difference in
the area and the relative position between the centers of
the dots included in the picture is calculated. Moreover,
the dot vector is encoded. The print dot compression data
module 55 includes data representative of the encoded dot
vector, the direction of the screen lines and the screen
ruling of the screen lines per unit length.
The print dot compressing algorithm makes use of the
fact that the picture included in the print dot image
element data 52 is composed of the dots and thus the
redundancy thereof is large. Consequently, the print dot
image element data 52 is effectively compressed.
The print dot pattern compressing algorithm will be
described below in detail.
The print dot image element data 52 is constituted
by the data representative of the picture composed of the
dots, as mentioned above. Fig. 9 shows a part of the
picture included in the print dot image element data 52.
Dots 81 included in the print dot image element data 52
are arranged in accordance with the arrangement defined
by the print rule. The dots 81 are arranged on screen lines
82.
Fig. 10 is a flowchart showing the print dot pattern
compressing algorithm. At first, as shown in Fig. 10, the
print dot pattern compressing algorithm respectively
calculates the areas and positions of the center of the
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dots 81 included in the print dot image element data 52
(Step Sil).
Shapes of the dots 81 may be distorted. This is
because the print dot image elemerit data 52 is generated
from an image 30 printed on a paper. The dot 81 is printed
so as to be square while the image 30 is printed on the
paper. In the process for printing the image 30 on the
paper, however, factors of ink permeation and the like
cause the shapes of the dots to be distorted. Thus, the
print dot image element data 52 generated from the image
30 printed on the paper is constituted by the data
representative of the dots 81 whose shapes are distorted.
The respective areas of the dots 81, whose shapes
are distorted, are calculated by any of two methods as
descried below.
As shown in Fig. 11, a first method of calculating
the area firstly extract an outline of the dot 81 indicated
by the print dot image element data 52. Curvature points
are determined counterclockwise or clockwise in turn on
the outline of the extracted dot 81. The curvature point
is a point at which an extension direction of the outline
of the dot 81 is changed. Curvature points a to k are
determined in turn.
Moreover, vectors for connecting two curvature
points adjacent to each other are determined. Vectors 83a
to 83k are determined. The vectors 83a to 83k make the
round of the outline of the dot 81. The sum of the vectors
83a to 83k is a 0 vector.
Next, a square 84 is determined so that the square
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84 is circumscribed about a polygon having curvature
points a to k as the vertexes, and a length of sides thereof
is minimum. Let the four vertexes of the square 84 be
respectively vertex A, B, C and 'D . An area of the dot 81
is calculated by subtracting an area of a portion that is
located inside the square 84 and located outside the
polygon having the curvature points a to k as the vertexes,
from the area of the square 84. That is, it is calculated
by subtracting the areas of a polygon Acbak, a triangle
lo Bdc, a triangle eCg, a triangle hDi and a triangle ijk,
from the area of the square 84.
A second method of calculating the area firstly
determines scanning lines 85, as shown in Fig. 12. The
scanning lines 85 are determined so as to be extended in
the x-axis direction. The scanning lines 85 can be
determined so as to be extended in a different direction,
for example, a y-axis direction. The scanning lines 85
are arranged in parallel to each other at an equal interval.
The dot 81 is scanned along the scanning lines 85. A
boundary 86 of the dot 81 is detected from the change of
graduation. An area inside the boundary 86 is an area of
the dot 81.
The area of the dot 81 having any shape is calculated
by using any of the first method and the second method as
mentioned above.
Moreover, the position of the center of the dot 81
is calculated as follows. At first, as shown in Fig. 11,
the square 84, which is circumscribed about the dot 81,
is determined in which the length of one side is minimum.
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The position of the central point of the dot 81 is defined
as an intersection 0 of diagonals AC, BD of the square 84.
Here, the following equation is established:
AO = BO = CO = DO.
A position at a certain dot is defined as a position
of a center of the dot. Hereafter, if a position of a dot.
is noted, the position of the dot implies the position of
the center of the dot. Also, a distance between certain
two dots implies a distance between a center of one dot
and a center of another dot.
Moreover, as shown in Fig. 10, screen lines are
extracted (Step S12 ). The screen lines are extracted by
using any of the following three methods.
A first method of extracting the screen lines
firstly extracts the dots having a larger area than a
predetermined area, from the dots 81. Hereafter, ones of
the dots 81, which have the larger area than the
predetermined area, are referred to as screen line
extraction dots. Fig. 13 shows the arrangement of centers
97 of the screen line extraction dots. The centers 97 of
the screen line extraction dots are substantially aligned
in a certain direction. Straight lines that extend in the
direction to pass through the centers 97 of the screen line
extraction dots are recognized as screen lines 98. In
order to determine the screen lines 98, a least-squares
method is used if necessary.
A second method of extracting the screen lines
firstly extracts four dots from the dots 81, as shown in
Fig. 14. At this time, the four dots are extracted such
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that the centers o:= the extracted dots are substantially
vertexes of a square. Hereafter, the extracted dots 81
are referred to as dots 811 to 814.
A plurality of straight lines 88 and a plurality
of straight line5 5y showii in Fig. 14 are recognized as
the candidates of the screen lines. 'Here, the straight
lines 88 are the straight line that extend in the same
direction as the sides of 871 of the square 87 with the
four centers of the dots 811 to 814 as the vertexes thereof
and passes through the centers of the dots 811 to 81,. On
the other hand, as for the straight lines 89, the straight
lines 89 that ext:.nci i.;r: di=Ggonal =lines 67-, of the square
87 and pass thrcu;h the: :,enters c+f the dots 811 to 814 are
recognized as the candidates of the screen lines.
The reasori wiiy botY, of the straight lines 88, 89
can be the candidates of the s.creen line is that the dots
811 to 814 have any of the two arrangements is described
below. As shoW n in Fig. 15 (a) , there may be a case that
two dots each of dots 81, to 81d ar-e located on two screen
lines 90, 91.
Also, as shown ir. Fig. 15 (b) , there may be a case
that one of the dots 811 to 81+ is located on a screen llne
92, another one of the dots 811 to 814 is located on a screen
line 93, and the remaining two of the dots 81, to 814 are
located cn a screen line 94 that is located between the
screen lines 92, 93.
The extraction of the four dots 811 to 814 does not
give the basis of iudgina whether the dots 811 to 81, have
the arrangement shown in Fig. 15 (a) or the arrangement
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shown in Fig.- 15 ( b). Therefore, both the straight lines
88 and the straight lines 89 are recognized as the
candidates of the screen lines. Which of the straight
lines 88 and the straight lines 89 are the true screen lines
is judged from an angle between the straight lines 88 and
an X-axis and/or a x-axis, and an angle between the
straight lines 89 and an X-axis and/or a x-axis.
A third method of extracting the screen lines
extracts the screen lines from the shape of a dot 81, as
shown in Fig. 16. In printing, the dot 81 is printed such
that an extending direction of a side of a square, which
is an outline of the dot 81, or an extending direction of
a diagonal line comes in coincidence with the direction
of the screen lines. The printed dot 81, even if its shape
is slightly distorted, has a shape of a substantial square.
In the third method of extracting the screen line, straight
lines, which extend in an extending direction of a side
815 of the square or an extending direction of a diagonal
line 816 and pass through the center points of the dots
81, are recognized as the screen lines.
Moreover, as shown in Fig. 10, a screen angle 0
between the extracted screen lines and the X-axis is
calculated (Step S13). As shown in Fig. 17, let points
A, C be located on the screen line 94.
Let a point B be a foot of a perpendicular line
dropped from the point C to a straight line 95 parallel
to the X-axis through the point A. The screen angle 8 is
given by:
6 = tan-1 (AB/BC) .
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The screen arigle 0 may be noted as (nAB, nB,) by using a
number nAe of dots located on a line segment AB and a number
nBC of dots located on a line segment BC.
The screen angle 0 is added to the above mentioned
print dot compression data module 55. When a picture is
restored from the print dot compression data module 55,
the screen angle 0 is used, which is included in the print
dot compression data module 55.
Moreover, as shown in Fig. 10, a screen ruling D is
calculated (Step S14). The screen ruling D is calculated
as f ollows . As shown in Fig. 18, the number of the screen
lines 96 that intersect a straight line BC having a unit
length is calculated as the screen ruling D where the
straight line BC is a straight line orthogonal to screen
lines 96 extracted at a step S12.
The screen ruling D is given by:
D = 1/ds,
where ds is the interval between the screen lines 96 is.
The screen ruling D is added to the above mentioned print
dot compression data module 55. When the picture is
restored from the print dot compression data module 55,
the screen ruling D is used which is included in the print
dot compression data module 55.
Moreover, as shown in Fig. 10, dot vectors are
calculated (Step S15). The process for calculating the
dot vectors from dots 101 aligned on screen lines 102 as
shown in Fig. 19 will be described below.
One of the dots 101 is defined as a characterizing
dot. For the characterizing dot, a dot vector is
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determined which is an eighth-dimension vector. Here a
firstly determined characterizing dot for one screen line
among the screen lines 102 is referred to as a standard
characterizing dot. If the determined characterizing dot
is the standard characterizing dot, a position and an area
of the standard characterizing dot are added to the print
dot compression data module 55.
In this embodiment, at first, a dot vector po is
determined with a dot 101o as the characterizing dot. The
dot 101o is the standard characterizing dot, and a position
and area thereof are added to the print dot compression
data module 55.
Next, an xl-axis, an x2-axis , an x3-axis and an x4-axis
are determined with the center of the characterizing dot
as an origin. The xl-axis direction is the direction
parallel to the screen lines 102. The x2-axis direction
is the direction vertical to the screen lines 102. The
x'-axis direction and the x4-axis direction are the
directions angled at 450 with reSpect to the screen lines
102. The xl-axis, the xz-axis, the x'-axis and the x4-
axis are determined with the dot 101o as the origin.
Two of the elements of the dot vector po are
determined in relation to the xl-axis. A vector having
the two of the elements of the dot vector po determined
in relation to the xl-axis as the elements thereof is
referred to as a dot small vector plo. In the same way,
vectors having the two of the elements of the dot vector
po respectively determined in relation to the xZ -axis, the
x'-axis and the x4-axis from as the elements thereof are
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referred to as a dot small vector pZO , a dot small vector
p3o and a dot small vector p4o, respectively.
At first, the dot small vector plo is determined. The
dot small vector plo is calculated from the positions and
the areas of the dots 1011 to lOln located on the xl-axis,
in the dot 101.
In order to determine the dot small vector plo, an
imaginary coordinate system Qlis firstly determined. In
the imaginary coordinate system Q1 , as shown in Fig. 20,
a dot 1010, which is the characterizing dot, is placed at
the origin 01. Moreover, dots 1011, to l Olln are placed at
points P11 to Pln, respectively.
The coordinates of the points P', to Pln are determined
as follows. Let an x-coordinate of the point Pli of the
points P11 to Pln be xli, and a y-coordinate thereof be yli.
At this time, the x-coordinate xli of the point P11 is
determined so as to be equal to a distance between a dot
l O 11i and the dot 101o in the actual space. Moreover, the
y-coordinate yli is determined by the following equation:
yli = Sli - Sp
where S11 is an area of the dot 10111 and So is an area of
the dot 1010.
Moreover, let qlj be a position vector at the point
P11 in the imaginary coordinate system Q'. The position
vector qli is given by:
1 q 1 =(xli= Y~j) =
Moreover, an adjacent dot vector ali is defined as follows :
al = 1 - 1
i H i ~! 1-i =
The adjacent dot vector ali is the difference between the
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position vectors of two dots adjacent to each other. The
adjacent dot vector ali is given by:
ali = (Axli AYli ) .
where
i i i
~x = x i - x i_1
Dyli = y11 - yli_1
The dot small vector po1 is determined to be equal
to a position-vector qlk when k' is defined as being the
minimum value of an integer k satisfying the following
condition.
Condition: for all integers J that are 2 or more and k or
less:
I X1 I 5 Xmax = ... (a)
lYljl s Ymax= ...(b)
OX1 5 Xdif ... ( c)
DY1 j :~'- Ydif ... ( d )
where Xmax= Ymax, Xdif and yaif are predetermined standard
values.
In detail, they are determined as follows. At first,
for j being 2, it is judged whether or not the conditions
(a) to (d) are satisfied. If any of the conditions (a)
to (d) is not satisfied, a dot small vector plo is determined
as a position vector qll.
Next, for j being 3, it is judged whether or not the
conditions (a) to (d) are satisfied. If any of the
conditions (a) to (d) is not satisfied, the dot vector plo
is determined as a position vector q1z.
After that, while j is incremented in turn, it is
judged whether or not the conditions (a) to (d) are
CA 02499286 2000-12-20
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satisfied. The dot small vector plo is determined as a
position vector qk. when any of the conditions (a) to (d)
is firstly dissatisfied for j being k' +1 .
As for a case shown in Fig. 20, when j is 2 or more
and 4 or less, all of the conditions (a) to (d) is satisfied.
However, when j=5, lYlsj > Ymax and thus the condition (b)
is not satisfied. Therefore, k' is determined as being
4. That is, the dot small vector plo is given by:
1 P 0 = q 1
4-
1o The dot small vector plo equal to the position vector
qk. is a vector from the origin 0, that is, the point Po
to the point qk.. Here, it holds:
1 P 0 = ( Xl k=, Y 1
k')
_( X1 k. , S1 k. - So ).
As mentioned above, the xlk is the distance between the
dot 101o and the dot 1011k.. Moreover, the Slk.-So is the
difference in the area between the dot 1010 and the dot
1011k. . That is, the dot small vector plo is the vector
having as the elements the distance between the dot 1010
and the dot 101'k and the difference in the area between
the dot 101o and the dot 1011k. Thus, the dot small vector
plo includes the information of the positions and the areas
of the dots 1011 to lOlk..
The same operation is carried out for the x2 -axis,
the x'=axis and the x -axis, to respectively determine a
dot small vector pZo, a dot small vector p'o and a dot small
vector p4o. The dot small vector pzo is calculated from
dots 101Z1 to 1012n of the dots 101, the dots 101Z1 to 101Zn
being located on the xz -axis. The process for calculating
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the dot small-vector p2o from the dots 10121 to 101Zn located
on the x2-axis is identical to the process for calculating
the dot small vector plo from the dots 10111 to 1011n located
on the xl-axis.
Also, the dot small vector p'o is calculated from dots
10131 to 1013õ of the dots 101, the dots 1013 1 to 1013 n being
located on the x' -axis. The process for calculating the
dot small vector p'o from the dots 10131 to 1013n located
on the x'-axis is identical to the process for calculating
the dot small vector plo from the dots 10111 to 1011, located
on the x'-axis.
The dot small vector p o is calculated from dots 101 1
to 101'n of the dots 101, the dots 101 1 to lOl4n being located
on the x` -axis. The process for calculating the dot small
vector p4o from the dots 10141 to 1014n located on the x4-axis
is similar to the process for calculating the dot small
vector plo from the dots 10111 to 1011n located on the xl-axis .
The dot vector po is determined from the dot small
vector pla , the dot small vector pZO the dot small vector
p'o and the dot small vector p`o .
The dot vector po includes the information
representative of the positions and areas of the dots that
are located on the xl-axis and between the dot 1010 and
the dot 101'. Moreover, the dot vector poincludes the
information representative of the positions and areas of
the dots that are located on the x2-axis and between the
dot 101o and the dot 1012. Moreover, the dot vector po
includes the information representative of the positions
and areas of the dots that are located on the x3-axis and
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between the dot 101o and the dot 101' Moreover, the dot
vector poincludes the information representative of the
positions and areas of the dots that are located on the
x -axis and between the dot 101o and the dot 1014.
Following the calculation of the dot vector po,
another dot 1011k. that is the end point of the dot small
vector pla is determined as the characterizing dot, and
the other dot vector pk. is determined. After that,
towards a+xl-axis direction, the calculations of the dot
vectors are carried out in turn.
The calculation of the dot vector is similarly
performed on the other screen lines. The calculation of
the dot vector is performed on all the dots included in
the print dot image element data 52.
The thus-generated dot vector p is the eighth-
dimensional vector, and the elements thereof is
represented by:
p X1 , AS1 , x2 , OS2 , X3 , OS3 , X4 , OS4 ~ i
where
xl is a distance between a characterizing dot and an
xl dot that is another dot located on the x'-axis;
OS1 is the difference in the area between the
characterizing dot and the xl dot;
x2 is a distance between the characterizing dot and
an x2 dot that is another dot located on the xZ-axis;
AS3 is the difference in the area between the
characterizing dot and the x3 dot;
x3 is a distance between the characterizing dot and
an x3 dot that is the different dot located on the x'-
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axis;
AS3 is the difference in the area between the
characterizing dot and the x3 dot;
x` is a distance between the characterizing dot and
an x4 dot that is another dot located on the x` -axis; and
OS` is the difference in the area between the
characterizing dot and the x' dot.
The calculated dot vector is encoded to calculate
the print dot compression data module 55 (Step S16).
During encoding, the dot vector is compressed to increase
the compression ratio.
By the above mentioned processes, the print dot image
element data 52 is compressed in accordance with the print
dot pattern compressing algorithm to generate the print
dot compression data module 55.
On the other hand, as shown in Fig. 1, the line picture
image element data 53 is compressed.in accordance with the
line picture compressing algorithm to generate the line
picture compression data module 56 (Step S05). In the line
picture compressing algorithm, an edge of an image element
is detected, and a vector indicative of a direction of the
edge is then calculated. Moreover, the vector is encoded
to thereby generate the line picture compression data
module 56.
The line picture compressing algorithm will be
described below in detail.
The line picture compressing algorithm is explained
by using a exemplary case when a original picture 110 shown
in Fig. 21 is compressed in accordance with the line
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picture compressing algorithm. At first, as shown in Fig.
22, the original picture 110 is scanned along a scanning
line 111, and a graduation of the original picture 110 are
detected. The scanning line 111 is parallel to the x-
axis. Edges 112 of the original picture 110 are detected
from the change of the graduation. The edges 112 are
located where the graduation is sharply changed.
The direction of the scanning line 111 is not limited
to the direction para11e1totheX-axis. The scanning line
111 may be parallel to the Y-axis, and it may be another
direction.
Scanning the original picture 110 along the scanning
line 111 to detect the edge 112 enables to increase the
speed of the detection of the edge 112 of the original
picture 110. This is desirable in that the speed of the
compression of data representative of the picture
indicated as the line picture is made faster.
Fig. 23 shows the detected edges 112. The detected
edges 112 are linked to thereby,generate an outline. At
first, an edge 1121 that is the closest to the origin 0
is selected. Moreover, an edge 1122 having a point thereon
which is the farthest from the origin 0 is selected. The
edge 1121 and the edge 112Z are linked to thereby generate
the outline.
Moreover, an edge 1123 that is the next closest to
the origin 0 and an edge 1124 that is the second farthest
from the origin 0 are selected. The edge 1123 and the edge
1124 are linked to thereby generate an outline.
Even if other edges are present, they are similarly
CA 02499286 2000-12-20
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linked to thereby generate the outline.
However, as shown in Fig. 24, if an area a of a region
113 inside an outline generated by a link connecting an
edge 1125 and an edge 1126 is smaller than a predetermined
value 1, the edge 1125 and the edge 1126 are judged to be
noises. The edge 1125 and the edge_1126 are discarded.
Fig. 25 shows the generated outline. An outline 1141
is generated by the link between the edge 1121 and the edge
1122. An outline 1142 is generated by the link between the
edge 1123 and the edge 1124.
Outline vectors 1151 to 1154 are defined along the
outline 1141. Outline vectors 1155 to 1158 are defined
along the outline 1142. Moreover, position vectors 1161,
1162 representative of the positions of the outlines 1141,
,1142 are respectively determined.
If necessary, smoothing is performed on the outline
to reduce the number of the outline vectors.
As shown in Fig. 26, let us suppose that outline
vectors OA, AC, CD and DB are defined along. the outline.
This corresponds to the case when a convex outline is
locally defined. In this case, it is determined as follows
whether the outline vectors OA, AC, CD and DB are left as
they are or the outline vectors OA, AC, CD and DB are
integrated and only the outline vector OB is left.
A straight line 116 is defined which passes through
the point 0 and is parallel to the X-axis. Let the point
B' be a foot of a perpendicular line dropped from the point
B to the straight line 116. In this case, the outline
vectors OA, AC, CD and DB are integrated to thereby
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generate the outl_ne vector 0B when a length Iõ- of the
line segment AC and a length I. of the line segment BB'
satisfy the following equation:
IBB. - Iac G 1, ...(e)
where (xlis a predetermined standard value. If the
equation (e) is not satisfied, the outline vectors OA, AC,
CD and DB are left ac they are. The case of satisfying
the equation (e) is the case that the convex portion
existing on the outline is small. If the equation (e) is
satisfied, the convex portion existing on the outline is
judged to be small, and the convex portion is ignored.
It may be judged whether the outline vectors OA, AC,
CD and DB are left in their original states or only the
outline vectar OB is left can be judged on the basis of
the following condition:
Soaa= - SACO ~ a2, ...(f)
where SAco is an area of a triangle ACD and SOBe. is an area
of a triangle OBB' . cx 2 is a predetermined standard value.
If the condition ( f) is satisfied, the outline vectors OA,
AC, CD and DB are integrated to thereby generate the
outline vector OB. if the condition (f) is not satisfied,
the outline vectors OA, ,AC, CD and DB are left as they are.
The case that the conuition (f) is satisfied is the case
that the convex portion existing on 'the outline is small.
If the condition (f) is satisfied, the convex portion
existing on the outline is judged to be small, and the
convex portion is ignored.
Also, as sho-.,yn in Fig. 27, let us suppose that outline
vectors OA. AB are defined along an outline. In this case,
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it is determiaed as follows whether the outline vectors
OA, AB are left as they are or the outline vectors OA, AB
are integratad in=co an outline vector OB.
A straight line 117 is defined which passes through
a point 0 and is parallel to an X-axis. A point A' and
a point B' is respective;.y defined as being feet of
perpendicular lines dropped from a point A and a point B
to the straight line 117. Moreover, is defined as
being an area of a triangle OAA' , and S. is defined as
an area of a triangle OBB'. The outline vectors OA. AB
are integrated to tliereby generate an outline vector aB,
if they satisfy, br2 following condition:
S068' - SACD ce 't = ( , )
If the condition ( g) is not satisfied, the outline vectors
is OA, AB are left as they are. The case when the condition
(g) is satisfied corresponds to the case that the curvature
of the outline is ).ocal and small. If the condition (g)
is not satisfied, the curvature of the outline is ignored.
The outline vec=tor and the='position vector, which
20- are generated by the above-mentioned processes, are
encoded. Moreover, graduation data is encoded for
indicating the graduations of image elements existing
between the outlines. It should be noted that the number
of the graduazions migh t be 2, or might be more, for example,
25 256.
The encoded outline vector and graduation
constitute title compressed pictu=e data. The compression
of the picture based on the line picture compressing
algorithm is completed by the above mentioned processes.
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The line picture image element data 53 is compressed in
accordance with the line picture compressing algorithm to
thereby generate the line picture compression data module
56.
As shown in Fig. 1, the free micro dot compression
data module 54, the print dot compression data module 55
and the line picture compression data module 56 are
integrated into one piece of data to generate a
collectively compressed data module 57 (Step S06). The
collectively compressed data module 57 may be recorded on
a recording medium to be used.
The compression of the page space image data 50 is
completed by the above mentioned processes. It should be
noted that the free micro dot compression data module 54,
the print dot compression data module 55 and the line
picture compression data module 56 may not be integrated
and they are stored as different files.
A process for restoring the original picture from
the collectively compressed data module 57 will be
described below. At first, as shown in Fig. 28, the free
micro dot compression data module 54, the print dot
compression data module 55 and the line picture
compression data module 56 are restored from the
collectively compressed data module 57 (Step S21). It
should be noted that the step S21 is not carried out if
the free micro dot compression data module 54, the print
dot compression data module 55 and the line picture
compression data module 56 are not integrated and they are
stored as the different files.
CA 02499286 2000-12-20
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The free micro dot compression data module 54 is
restored in accordance with a free micro dot pattern
restoring algorithm to generate a free micro dot temporary
data 58 is generated (Step S22). The reverse conversion
to the conversion done in the above-mentioned free micro
dot pattern compressing algorithm is carried out in the
free micro dot pattern restoring algorithm.
That is, the free micro dot compression data module
54 includes the data into which the pattern of the above
1o mentioned area patch 71 is encoded and compressed. At
first, a symbol representative of the pattern is decoded,
and then the pattern of the area patch 71 is further
reproduced. The patterns of the area patch 71 are arrayed
corresponding to their original states to generate the
free micro dot temporary data 58. The free micro dot
temporary data 58 includes the data representative of the
portion of the free micro dot in the original image 30.
The print dot compression data module 55 is restored
in accordance with a print dot.restoring algorithm to
generate a print dot temporary data (Step S23).
As mentioned above, the dot vector p determined when
it is determined as the characterizing dot is encoded into
the print dot compression data module 55.
As mentioned above, the dot vector p is represented
by:
p = ( xl , es'., xz , eSZ, x3 , As3 , x , Os4 ) ,
where
xl is the distance between the characterizing dot
and the xl dot that is the other dot located on the xl-axis;
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OS1 is the difference in the area between the
characterizing dot and the xi dot;
xZ is the distance between the characterizing dot and
the xZ dot that is the other dot located on the x2-axis.
OS' is the difference in the area between the
characterizing dot and the x3 dot;
x3 is the distance between the characterizing dot
and the x3 dot that is the other dot located on the x3-axis;
AS3 is the difference in the area between the
characterizing dot and the x3 dot;
x` i_s the distance between the characterizing dot and
the x4 dot that is the other dot located on the x'-axis.
AS` is the difference in the area between the
characterizing dot and the x4 dot.
Fig. 29 is a flowchart showing the print dot
restoring algorithm. At first, the print dot compression
data module 55 is restored (Step S31).
The screen ruling D and the screen angle 0 are
extracted from the restored print dot compression data
module 55 (Step S32). The direction and the number of the
screen lines determined for the picture to be restored are
determined.
The position and area of a standard characterizing
dot are extracted from the restored print dot compression
data module 55 (Step S33).
Moreover, the dot vector p determined for the
standard characterizing dot is extracted. Moreover, the
position and area of other dots are determined by the
interpolation, on the basis of that dot vector p (Step
CA 02499286 2000-12-20
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S34)
Fig. 30 shows the process for determining the
position and area of the other dots. A screen line 121
is restored on the basis of the screen ruling D and the
screen angle 6 extracted at the step S32.
Moreover, the standard characterizing dot 122 is
restored on the basis of the position and area of the
standard characterizing dot 122 extracted at the step S32.
Next, an xl-axis, an xZ-axis, an x'-axis and an x4-axis are
determined, as shown in Fig. 30, using the standard
characterizing dot 122 as an origin.
Moreover, an area and a point position of a center
of a characterizing dot 1231 located on the xl-axis are
determined on the basis of the elements xl and AS' of the
dot vector p determined for the standard characterizing
dot 122. The characterizing dot 1231 is restored.
Moreover, on the basis of the areas and positions of the
characterizing dot 1231 and the standard characterizing
dot 122, an area and a position of.a dot 1241 located between
them are determined by an interpolation, on the basis of
the element xl and the element AS'. The area of the dot
1241 ranges between the area of the standard characterizing
dot 122 and the area of the characterizing dot 1231. The
dot 1241 is restored.
Moreover, an area and a position of a characterizing
dot 1232 located on the xZ-axis are determined on the basis
of the element x2 and AS2 of the dot vector p determined
for the standard characterizing dot 122. The
characterizing dot 123 z is restored. On the basis of the
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areas and positions of the characterizing dot 1232 and the
standard characterizing dot 122, an area and a position
of a dot 1242 located between them are determined by an
interpolation, on the basis of the element xZ and the
element OS2. The area of the dot 1242 ranges between the
area of the standard characterizing dot 122 and the area
of the characterizing dot 1232. The dot 124 2 is restored.
Moreover, an area and a position of a characterizing
dot 1233 located on the x'-axis are determined on the basis
of the elements x' and OS' of the dot vector p determined
for the standard characterizing dot 122. The
characterizing dot 123' is restored. On the basis of the
areas and positions of the characterizing dot 123' and the
standard characterizing dot 122, an area and a position
of a dot 1243located between them are determined by an
interpolation, on the basis of the element x3 and the
element OS3. The area of the dot 124' ranges between the
area of the standard characterizing dot 122 and the area
of the characterizing dot 1233. The dot 1243 is restored.
Moreover, an area and a position of a characterizing
dot 1234 located on the x4-axis are determined on the basis
of the element x4 and OS' of the dot vector p determined
for the standard characterizing dot 122. The
characterizing dot 1234 is restored. On the basis of the
areas and positions of the characterizing dot 1234 and the
standard characterizing dot 122, an area and a position
of a dot 1244located between them are determined by an
interpolation, on the basis of the element x" and the
element AS4. The area of the dot 1244 ranges between the
CA 02499286 2000-12-20
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area of the standard characterizing dot 122 and the area
of the characterizing dot 1234. The dot 1244 is restored.
In succession, another characterizing dot and
another dot are restored from a different dot vector
determined for the characterizing dot 1231. Similarly,
other characterizing dots and other dots are restored from
other dot vectors determined for the other characterizing
dot located on the same screen line 121 as the standard
characterizing dot 122.
Moreover, the operations identical to the above
mentioned operations are performed on all the standard
characterizing dots located on other screen lines 121, and
other all characterizing dots and dots are restored. The
restoration of the image element constituted by the print
dots is completed (Step S35). The restored image element
is stored as the print dot temporary data 59.
On the other hand, as shown in Fig. 28, the line
picture compression data module 56 is restored in
accordance with a line picturerestoring algorithm to
generate a line picture temporary data 60 (Step S24).
As mentioned above, the position vector, the outline
vector, and the graduation data representative of the
graduation of the image element existing between the
outline are encoded in the line picture compression data
module 56. At first, the outline vectors 1151 to 1158 and
the position vectors 1161, 1162 are decoded. The outline
vectors 115, to 1158 are arranged at positions indicated
by the position vectors 1161, 1162, as shown in Fig. 31.
The arranged outline vectors 115, to 1158 constitute
CA 02499286 2000-12-20
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outlines 114i , 114., .
Moreover, a region 117 between the outlines 1141, 1142
is embedded with the graduation indicated by the
graduation data encoded in the line picture compression
data module 56 to complete the restoration of the image
element composed of' the line pictures. The restored image
element is stored as the line picture temporary data 60.
At this time, the region 117 between the outlines 1141,
1142 can be embedded with a different pattern. A special
picture process can be achieved by embedding the different
pattern in the region 117 between the outlines 1141, 1142.
In this case, data such as music and voice can be inserted
into the region 117 as digital watermark.
As shown in Fig. 28, the free micro dot temporary
data 58, the print dot temporary data 59 and the'line
picture temporary data 60 are synthesized to thereby
generate a restoredimage data 61 (Step S25) . The restored
image data 61 is representative of the image substantially
equal to the original page space image data 50.
In the compressing method and the restoring method
of the image data in this embodiment, the image on the paper
captured by the scanner and the like is classified into
the image elements and extracted. Moreover, each of the
image elements is compressed and restored in accordance
with the algorithm corresponding to it. Thus, the
compression ratio is improved, and the deterioration in
the picture quality-caused by the compression and
restoration is suppressed.
Moreover, in the compressing and restoring method
CA 02499286 2000-12-20
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of the image=data in this embodiment, the dot vector is
generated from the dots included in the picture. The
redundancy of the dots is effectively utilized to thereby
improve the compression ratio.
In this embodiment, it should be noted that the print
dots could be extracted by the following process to thereby
generate the print dot image element data 52 at the step
S02.
At first, the portion corresponding to a set of point
l0 regions having an area smaller than a maximum area of a
print dot defined by the print rule is extracted from the
page space image data 50. As for the point regions, both
of the possibility that it is the print dot and the
possibility that it is not the print dot should be
considered. Next, positions of centers of the point
regions are respectively calculated. The calculating
method is identical to the methodiof calculating the
positions of the centers of the print dots, in the above
mentioned print dot compressing algorithm.
Moreover, it is judged whether or not the screen
lines can be determined at an equal interval so as to pass
in the vicinities of the centers of the point regions. If
the screen lines can be determined, the set of the point
regions is judged to be the set of the print dots. The
set of the point regions is extracted to thereby generate
the print dot image element data 52.
Also, in this embodiment, a color image may be
compressed and restored. In this case, as shown in Fig.
32, a page space image data can be component-divided for
CA 02499286 2000-12-20
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each color.
In the same way of the compression of the above-
mentioned monochrome image, the color image printed on the
page space is captured to thereby generate a color page
space image data 62 (Step S41).
The color page space image data 62 is component-
divided for each color (Step S42). From the color page
space image data 62, a component of cyan (C) is extracted
to thereby generate a blue component page space image data
63a. A component of magenta (M) is extracted from the
color page space image data 62 to thereby generate a red
component page space image data 63b. A component of yellow
(Y) is extracted from the color page space image data 62
to thereby generate a yellow component page space image
data 63c. A component of black (K) is extracted from the
color page space iinage data 62 to thereby generate a black
component page space image data 63d. That is, the color
page space image data 62 is component-divided into CMYK
system.
The image elements are extracted and classified in
the same way of the step S02 shown in Fig. 1, for each of
the blue component page space image data 63a, the red
component page space image data 63b, the yellow component
page space image data 63c and the black component page
space image data 63d (Step S43). A blue component free
micro dot image data 64a, a red component free micro dot
image data 64a, a yellow component free micro dot image
data 64c and a black component free micro dot image data
64d, each of which is representative of the picture
CA 02499286 2000-12-20
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composed of the free micro dots, are respectively
generated from the blue page space image data 63a, the red
component page space image data 63b, the yellow component
page space image data 63c and the black component page
space image data 63d, respectively.
Moreover, a blue component print dot image data 65a,
a red component print dot image data 65b, a yellow
component print dot image data 65c and a black component
print dot image data 65d, each of which is representative
of the picture composed of the print dots, are respectively
generated from the blue component page space image data
63a, the red component page space image data 63b, the
yellow component page space image data 63c and the black
component page space image data 63d.
Moreover, a blue component line picture image data
66a, a red component line picture image data 66b, a,yellow
component line picture image data 66c and a black component
line picture image "data 66d, each of which is
representative of the picture Composed of the pictures
having the strong edges, are respectively generated from
the blue component page space image data 63a, the red
component page space image data 63b, the yellow component
page space image data 63c and the black component page
space image data 63d.
The blue component free micro dot image data 64a,
the red component free micro dot image data 64b, the yellow
component free micro dot image data 64c and the black
component free micro dot image data 64d are compressed in
accordance with the above mentioned free micro dot pattern.
CA 02499286 2000-12-20
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compressing algorithm to respectively generate a blue
component free micro dot temporary data 67a, a red
component free micro dot temporary data 67b, a yellow
component free micro dot temporary data 67c and a black
component free micro dot temporary data 67d (Step S44).
The blue component print dot image data 65a, the red
component print dot image data 65b, the yellow component
print dot image data 65c and the black component print dot
image data 65d are compressed in accordance with the above
mentioned print dot compressing algorithm to respectively
generate a blue component print dot temporary data 68a,
a red component print dot temporary data 68b, a yellow
component print dot temporary data 68c and a black
component print dot temporary data 68c (Step S45).
The blue component line picture image data 66a, the
red component line picture image data 66b, the yellow
component line picture image data,66c and the black
component line picture image data 66d are compressed in
accordance with the above mentioned line picture
compressing algorithm to respectively generate a blue
component line picture temporary data 69a, a red component
line picture temporary data 69b, a yellow component line
picture temporary data 69c and a black component line
picture temporary data 69d (Step S46).
The blue component free micro dot temporary data 67a,
the red component free micro dot temporary data 67b, the
yellow component free micro dot temporary data 67c, the
black component free micro dot temporary data 67d, the blue
component print dot temporary data 68a, the red component
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print dot temporary data 68b, the yellow component print
dot temporary data 68c, the black component print dot
temporary data 68c, the blue component line picture
temporary data 69a, the red component line picture
temporary data 69b, the yellow component line picture
temporary data 69c; and the black component line picture
temporary data 69c are integrated to thereby generate a
collectively compressed data module 57' (Step S47). The
compression of the color page space image data 62 is
completed.
It should be noted that the color page space image
data 62 may be naturally component-divided not only into
the CMYK system but also into one of other color systems,
for example, an RGB system with a red (R) , a green (G) and
a black (B) as the three primary colors.
Also, in this embodiment, the calculation of the dot
vector is performed on all of the xl-axis, the xZ-axis.,
the x'-axis and the x4-axis. It should be understood that
it is not always required to calculate the dot vector p
for all of the xl-=axis, the x.2-axis, the x'-axis and the
x'-axis. However, as mentioned in this embodiment, it is
desired to calculate the dot vectors for a plurality of
axes of the xl-axis, the xZ-axis , the x3-axis and the x'-axis ,
since the compression ratio is improved.
Also, in this embodiment, the image can be enlarged
and contracted while the restored image data 61 is
generated. In this case, the free micro dot included in
the free micro dot temporary data 58 generated by the
restoration of the free micro dot compression data module
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54 is enlarged at an enlargement rate or contracted at
a contraction rate (3.
Moreover, an operation for enlarging or contracting
the image element is performed on the print dot temporary
data 59, as described below.
The case of the enlargement of the image element
included in the print dot temporary data 59 is described.
Let us suppose that the print dot temporary data 59
includes dots 131 to 139, as shown in Fig. 33. Let us
suppose that the dots 131 to 139 are located at points A
to H, respectively.
Let the image element including the dots 131 to 139
be enlarged at the enlargement rate , the point A being
the center of the enlargement. At first, as shown in Fig.
33, the dot 132 is virtually shifted to a point B1 located
on a straight line which passes the point A serving as the
center of the enlargement and the point B where the dot
132 is.located.
In this case,
= AB1 / AB.
The virtually shifted dot 132 is hereafter referred to as
a virtual dot 132'. An area of the virtual dot 132' is
equal to an area of the dot 132. It should be noted that
the virtual dot 132' is the virtually shifted dot and the
virtual dot 132' is not placed actually.
Next, a new dot is generated at a point at which a
dot is to be located in accordance with the print rule,
the point being one of the points located between the
virtual dot 132' and the dot 131 adjacent thereto on a side
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opposite to a direction in which the dot 132 is shifted.
The generated new dot is referred to as a dot 132". In
the case shown in Fig. 33, a position of the dot 132"
coincides with the position of the dot 132. An area of
the new dot 132" is determined by the interpolation of the
areas of the virtual dot 132' and the dot 131 located on
the side opposite to the direction in which the dot 132
is shifted, the dot 131 being one of the dots adjacent to
the dot 132. The interpolation is executed with reference
to the positions of the dot 131, the virtual dot 132' , and
the new dot 132".
The data representative of the area of the new dot
132" is recorded in the print dot temporary data 59, on
which the operation for enlarging the image element is
performed. At this time, the data representative of the
area of the virtual dot 132' is discarded.
Other dots are virtually shifted to further generate
new dots in the same way. The data representative of the
areas of the generated new dots is recorded in the print
dot temporary data 59. The dot 133 is virtually shifted
to a point C1 , and the dot 134 is virtually shif ted to a
point D1, respectively, and virtual dots 133', 134' are
determined.
At this time,
= AC1/AC = AD1/AD.
Moreover, new dots 133", 134" are generated at the same
positions as the dots 133, 134.
Moreover, the same operation is performed on the
other dots to determine the areas of the newly generated
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dots in turn: The enlargement of the image element is
completed by the above mentioned processes.
At this time, the enlargeinent rate can be partially
changed. This enables to generate the modified image
element.
Next, the case of the contraction of the image
element included in the print dot temporary data 59 is
described. Let us consider the case that the print dot
temporary data 59 includes dots 231 to 239, as shown in
Fig. 34. Let the dots 231 to 239 be located at points A
to H, respectively.
Let the image element include the dots 231 to 239
to be contracted at the contraction rate (3 with the point
A used as a center of contraction. At first, as shown in
Fig. 34, the dot 232 is virtually shifted to a point B1
located on a straight line which passes the point A serving
as the center of the contraction and the point B where the
dot 232 is located, and the shift generates a virtual dot
232'.
At this time,
AB1 / AB.
Also, an area of the virtual dot 232' is equal to an area
of the dot 232.
A new dot is generated at a point at which a dot is
to be located in accordance with the print rule, the point
being one of the points located between the virtual dot
232' and the dot 235-adjacent thereto on a side opposite
to a direction in which the dot 232 is shifted. The
generated new dot is referred to as a dot 232". In the
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case shown in'Fig. 34, a position of the dot 232" coincides
with the position of the dot 232. An area of the new dot
232" is determined by the interpolation between the areas
of the virtual dot 232' and the dot 235 adjacent to the
side opposite to the direction in which the dot 232 is
shifted. The interpolation is executed with reference t
the positions of the dot 235, the virtual dot 232', and
the new dot 232".
The data representative of the area of the new dot
232" is recorded in the print dot temporary data 59, on
which the operation for contracting the image element is
performed. At this time, the data representative of the
area of the virtual dot 232' is discarded.
Other dots are virtually shifted to further generate
new dots in the same way. The data representative of the
areas of the generated new dots is recorded in the print
dot temporary data 59. The dot 233 is virtually shifted
to a point C1, and the dot 234 is virtually shifted to a
point D1, respectively, and virtual dots 233', 234' are
determined.
At this time,
(3 = AC1 / AC = AD1 / AD.
Moreover, new dots 233", 234" are generated at the same
positions as the dots 233, 234.
Moreover, the same operation is performed on the
other dots, and the areas of the newly generated dots are
determined in turr.i. 'The contraction of the image element
is completed by the above mentioned processes.
In this case, the contraction rate (3 can be partially
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changed. Thi-s enables to generate the modified image
element.
Also, another modified restoration can be achieved
by adding various operating functions to the print dot
restoring algorithm besides the enlargement and the
contraction functions.
Moreover,theoperationforenlargingor contracting
the image element as described below is performed on the
line picture temporary data 60.
In the case of the contraction of the image element,
as shown in Fig. 35, the outline vector and the position
vector included in the line picture temporary data 60 are
multiplied by the contraction rate to thereby generate
an outline vector 117 and a position vector 118. The
graduation indicated,by the graduation data included in
the line picture temporary data 60 is embedded in a region
117a on a left side in a direction;in which the outline
vector 117 is oriented, and this achie.ves restoration of
the contracted image element.
Similarly, in the case of the enlargement of the
image element, as shown in Fig. 36, the outline vector and
the position vector included in the line picture temporary
data 60 are multiplied by the enlargement rate to thereby
generate an outline vector 119 and a position vector 120.
The graduation indicated by the graduation data included
in the line picture temporary data 60 is embedded in a
region 119a on a left side in a direction in which the
outline vector 119 is oriented, and this achieves
restoration of the enlarged image element.
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Also,'in the embodiment of the present invention,
the position information stored in the compression data
can be used to restore the image element with the image
element rotated.
Also, as mentioned above, in this embodiment, the
free micro dot pattern compressing algorithm is used to
compress the free micro dot image element data 51. In this
embodiment, instead of the free micro dot pattern
compressing algorithm, a f ree micro dot vector compressing
algorithm as described below may be used to generate the
free micro dot compression data module 54.
Let us consider the case of the compression of free
micro dots 1411 to 1415 shown in Fig. 37. At first,
positions of centers of the free micro dots 1411 to 1415
are determined in the same way as the above mentioned
process for determining the positions of the centers of
the print dots. The positions of the free micro dots 1411
to 1415 are represented by the positions of their centers.
Hereafter, the positions of the free micro dots 1411 to
1415 imply the positions of the centers of the free micro
dots 1411 to 1415.
Let a coordinate of the position of the free micro
dot 1411 among the free mi.cro dots 1411 to 1415 be ( xi , yl ).
Moreover, Let an area of the free micro dot 1411 be Si.
Free micro dot vectors rl to r3 are determined as
follows. At first, the free micro dot 1411 is selected.
The position and the- area of the free micro dot 1411 are
added to the free micro dot compression data module 54.
The free micro dot vector rl is the vector having as the
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elements thereof a relative position between the free
micro dot 1411 and the free micro dot 1412 and the deference
in the area between the free micro dot 1411 and the free
micro dot 1412. That is,
rl = (x2-x1i Y2'Y1= S2-S1) .
Similarly, the free micro dot vector r2 is the vector
having as the elements thereof a relative position between
the free micro dot 1412 and the free micro dot 141, and
the difference in the area between the free micro dot 1412
and the free micro dot 1413. That is,
rZ = (x3-x2, Y3-Y2= S3-SZ) . .
Similarly, the free micro dot vector r3 is given by:
r3 = (x4-x3= Y4'Y3= S4-S3) =
The free micro dot vectors rl to r3 are encoded to thereby
generate the free micro dot compression data module 54.
Moreover, in this embodiment, the free micro dot
image element data 51 may be compressed to generate the
free micro dot compression data module 54 in accordance
with a free micro dot data compressing algorithm, instead
of the above mentioned free micro dot pattern compressing
algorithm, the free micro dot data compressing algorithm
being described below.
In the free micro dot data compressing algorithm,
a region 210 including a free micro dot 212 is divided into
rectangular regions 211. Two sides of the rectangular
region 211 are oriented to the x-axis direction, and the
other two sides are-oriented to the y-axis direction.
Compression data is generated for each of the rectangular
regions 211.
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The method of generating a compression data is
described by exemplifying the generation of a compression
data for a rectangular region 211a of the rectangular
regions 211. At first, the positions where free micro dots
212a to 212c included in the rectangular region 211a
targeted for the ganeration of the ccmpression data exist
are recognized. r:creover, the distances between the
existence positions of the free micro do,ts 212a to 212c
and one side out o_ four sides of the rectangular region
211a are calculated.
In this embodiment, distances d,, db and d. between
a side 213 ..ex=*.er_2.ing in the y-axis direction and the
positions of -th.e free micro dots 212a to 212c are
res'pectively calculateri. The distances d,, d, and d, are
given by:
d, = xa xo
do = xz - xo , and
de = x, - xe,
where xa is an x-coordinzte of the:side 213, and xa, xD and
x, are x coordinates of the positions of the free micro
dots 212a to 212c, re.:pectivEi_r. The calculated
distances function as raembers of tthe compression data
generated for the rectangular region 211a. At this time,
a distance from a side extending in the x-axis direction
can be also calculated.
Moreover, an average of concentrations of the
regions inside the rectangular region 211a is calculated.
The average corresponds to a sum of the areas of the free
micro dots 212a to 21:.'c =.n a one-to-one relationship. As
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described later, the average of the concentrations of the
regions inside the rectangular region 211a is used to
restore the areas of the free micro dots 212a to 212c . The
average functions as another member of the compression
data generated for the rectangular region 211a. The
generation of the compression data for the rectangular
region 211a is cornpleted as mentioned above.
The compression data is also generated for other
rectangular regions 211 in the same way. The generated
compression data are integrated to thereby generate the
free micro dot compression data module 54.
The free micro dot compression data module 54
generated as mentioned above is restored as described
below. At first, the compression data generated for the
respective rectangular regions 211 are read out from the
free micro dot compression data module 54. As described
above, the compression data include-the distances between
the free micro dots included in the respective rectangular
regions 211 and the sides of the rectangular regions.
Moreover, they include the averages of the concentrations
of the regions inside the respective rectangular regions.
The distances between the free micro dots included
in the respective rectangular regions 211 and the sides
of the rectangular regions are recognized from the
compression data. The positions of the free micro dots
are restored on the basis of the distances.
Moreover, the averages of the concentrations of the
regions inside the respective rectangular regions 211 are
recognized from the compression data. As mentioned above,
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the areas of the free micro dots included in the respective
rectangular regions 211 are determined on the basis of the
averages. At this time, it is defined that the free micro
dots included in the respective rectangular regions 211
have the same area. The free micro dots included in the
respective rectangular regions 211 are restored. The
free micro dot temporary data 58 is restored from the free
micro dot compression data module 54 by the above mentioned
processes.
Also, in this embodiment, the following operation
may be performed on the image element included in the page
space image data 50 before the image element on which the
operation is performed is compressed. Moreover, the
following operation may be executed while the free micro
dot temporary data 58, the print dot temporary data 59 and
the line picture temporary data 60 are synthesized.
When all the image elements included in the free
micro dot temporary data 58, the print d'ot temporary data
59 and the line picture temporary data 60 are restored,
an OR operation is carried out. For example, let us
suppose that image elements A, B, C and D are included in
the free micro dot temporary data 58, the print dot
temporary data 59 and the line picture temporary data 60.
While all of them are restored, an OR thereof is generated
to be a restoration image element 61. It holds
X= A OR B OR C OR D,
where X is the restoration image element 61.
Also, when all the image elements included in the
page space image data 50 is compressed, an OR operation
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is carried out. For example, let us suppose that the image
elements A, B, C and D are included in the page space image
data 50. While all of them are compressed, an OR thereof
is used as image data to be compressed. It holds
X' = A OR B OR C OR D,
where X' is the image data to be compressed.
When only the common portion of the image elements
included in the free micro dot temporary data 58, the print
dot temporary data 59 and the line picture temporary data
60 is restored, an AND operation is carried out. Let us
suppose that the image elements A, B, C and D are included
in the free micro dot temporary data 58, the print dot
temporary data 59 and the line picture temporary data 60.
If the common portion of the image elements A, B is restored
as the restoration image data 61, it holds
X = A AND B,
where X is the restoration image data 61.
Also, when only the common portion of the image
elements included in the page space image data 50 is
compressed, an AND operation is carried out. For example,
let us suppose that the image elements A, B, C and D are
included in the page space image data 50. When the common
portion of the image elements A, B is compressed, a logical
product of the image elements A, B is used as image data
to be compressed. It holds
X.' = A AND B,
where X' is the image data to be compressed.
For the restoration of a portion besides a plurality
of image elements, the portion selected from among the
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image elements included in the free micro dot temporary
data 58 and the print dot temporary data 59 and the line
picture temporary data 60, an NOR operation is carried out.
For example, let us suppose that the image elements A, C
are included in the free micro dot temporary data 58, the
print dot temporary data 59 and the line picture temporary
data 60. If the image element except the image element
A and the image element C is restored, it holds
X = A NOR C,
where X is the restoration image data 61.
For the compression of a portion besides a plurality of
image elements, the portion being selected from among the
image elements included in the page space image data 50,
an NOR operation is carried out. For example, let us
suppose that the image elements A, C are included in the
page space image data 50. When the image element except
the image element A and the image element C is compressed,
it holds
X' = A NOR C,
where X' is the image data to be compressed.
Also, when a portion besides a common portion i_n the
plurality of image elements is restored, the portion being
selected from among the image elements included in the free
micro dot temporary data 58, the print dot temporary data
59 and the line picture temporary data 60, an NAND
operation is carried out. That is, for example, let us
suppose that the image elements A, C are included in the
free micro dot temporary data 58, the print dot temporary
data 59 and the line picture temporary data 60. When all
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the portions-except the common portions of the image
element A and the image element C are restored, it holds
X = A NAND C,
where X is the restoration image data 61.
Also, when a portion except a common portion of the
plurality.of image elements is compressed, the portion
being selected from among the image elements included in
the page space image data 50, a NAND operation is carried
out. For example, let us.suppose that the image elements
A, C are included in the page space image data 50. When
all the portions except the common portion in the image
element A and the image element C are compressed, it holds,
X' = A NAND C,
where X' is the image data to be compressed.
Also, the image elements included in the free micro
dot temporary data 58, the print dot temporary data 59 and
the line picture temporary data 60 may be restored using
the operation of an exclusive-OR. Let us suppose that the
image elements A, C are included in the free micro dot
temporary data 58, the print dot temporary data 59 and the
line picture temporary data 60. It may be defined that
X = A XOR C,
where X is the restoration image data 61.
Also, the image elements included in the page space
image data 50 can be compressed after carrying out the
exclusive-OR. Let us suppose that the image elements A,
C are included in the page space image data 50. It may
be defined that X' = A XOR C,
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where X' is the image data to be compressed.
Also, let us suppose that the image element A and
the image element B are included in the free micro dot
temporary data 58, the print dot temporary data 59 and the
line picture temporary data 60. Here, let the image
element B superimpose on the image element A. In this case,
Restoring the image.element A with a transmission process
enables the image element A to be visible in the portion
where the image elements A, B superimposes with each other.
Also, restoring the image element A through a non-
transmission process enables only the image element B to
be visible in the portion where the image elements A, B
superimpose with each other.
The selection of the image element to be compressed
from the image elements included in the page space image
data 50 may be dorie on the basis of a name given to each
image element, a size of an image of each image element,
a shape of an image of each image element, a color of an
image of each image element and, an image data amount of
each image element. In the same way, the selection of the
image element to be compressed from the image elements in
the free micro dot temporary data 58, the print dot
temporary data 59 and the line picture temporary data 60
can be done on the basis of a name given to each image
element, a size of an image of each image element, a shape
of an image of each image element, a color bf an image of
each image element and an image data amount of each image
element.
The above mentioned selection and operation
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processes enables to extract and restore the necessary
image elements and the feature image elements from the page
space image. For example, performing the compressing
process on only a photograph, only a sentence and only a
table from the page space is effective for a filing and
database establishment. Also, restoration of particular
image elements is effective for the reduction in-the
information processing amount when a large number of image
elements are distributed and read through the Internet.
In this embodiment, as mentioned above, the page
space image data 50 is generated from the image 30 located
on the page space, and the page space image data 50 is
compressed and restored. In this embodiment, another
image data that is not generated from the page space may
be compressed and restored instead of the page space image
data 50.
Also, in this embodiment, the image element data may
be classified and extracted in accordance with another
standard, at the step S02. For example, the
classification and extraction may be executed on the basis
of the component element. This enables to classify and
extract types, handwritten characters, seals, line
pictures, graphics, tints, graduation nets and photograph
nets. Also, the classification and extraction may be
executed on the basis of kinds of image. This enables to
classify and extract documents, comics, maps,
advertisements, tables sample and photographs.
(Second Embodiment)
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A compressing and restoring method of image data in
the second embodiment classifies pictures included in the
image data into a region in which a graduation is
continuously changed and a region in which a graduation
is not substantially changed, and then compresses and
restores the image data. The compressing and restoring
method of image data in the second embodiment will be
described below.
The compressing and restoring method of image data
of the second embodiment is executed with a hardware
resource. That hardware resource 10' includes an input
device 11, a CPU 2, a memory 3, a recording medium 4 and
a bus 5, as shown in Fig. 38. The input device 11, the
CPU 2, the memory 3 and the recording medium 4 are connected
to the bus 5. An image data 150 is inputted to the input
device 11. The CPU 2 carries out an operation for
compressing or restoring the image,data 150. The memory
3 stores the data generated.in the process for carrying
out the compressing method and the restoring method of the
image data in the second embodiment. The recording medium
4 stores the program for describing the procedures
included in the compressing method and the restoring
method in the image data of the second embodiment. The
CPU 2 is operated in accordance with the program. The bus
5 transmits the data to be exchanged between the scanner
1, the CPU 2, the memory 3 and the recording medium 4
Fig. 39 shows the image data compressing method in
the~second embodiment. At first, the image data 150 is
inputted to the input device 11. A picture represented
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by the image'data 150 includes a region in which the
graduation is continuously changed and a region in which
the graduation is not substantially changed. Image
elements that are composed of dots are placed in the region
in which the graduation is continuously changed. Image
elements that are not composed of the dots are placed in
the region in which the graduation is not substantially
changed.
The image data 150 is converted in a binary format
to generate a binary data 151 (Step S51). Moreover, the
difference betweeri the image data 150 and the binary data
151 is calculated to thereby generate a multi-valued data
152 (Step S52).
The image data 150 is divided into the binary data
151 and the multi-valued data 152. The region in which
the graduation is not substantially changed is extracted
from the image data 150 as the binary data 151. A portion
corresponding to the region in which the graduation is
continuously changed is extracted from the image data 150
as the multi-valued data 152. The image elements composed
of the dots as mentioned above are placed in the region
in which the graduation is continuously changed. The
multi-valued data 152 is constituted by the data
indicative of the dots.
The multi-valued data 152 is compressed in
accordance with the print dot compressing algorithm
explained in the first embodiment to generate a print dot
compression data module 154 (Step S53). Moreover, the
binary data 151 is compressed in accordance with the line
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picture compressing algorithm explained in the first
embodiment to generate a line picture compression data
module 155 (Step S54).
The print dot compression data module 154 and the
line picture compression data module 155 are integrated
to thereby generate a collectively compressed data module
156 (Step S55). The compression of the image data 150 is
completed by the above mentioned processes. The
collectively compressed data module 156 may be recorded
on the recording medium for the use thereof.
The process for restoring the collectively
compressed data module 156 will be described below.
As shown in Fig. 40, the collectively compressed data
module 156 is divided to restore the print dot compression
data module 154 and the line picture compression data
module 155 (Step S61).
The print dot: compression data module 154 is restored
in accordance with the print dot restoring algorithm
explained in the first embodiment to generate a print dot
temporary data 157 is generated (Step S62). The picture
composed of the dots is restored in the print dot temporary
data 157.
Moreover, the line picture compression data module
155 is restored in accordance with the line picture
restoring algorithm explained in the first embodiment to
generate a line picture temporary data 158 (Step S63).
Moreover, the print dot temporary data 157 and the
line picture temporary data 158 are image-synthesized to
thereby generate a restoration dot data 160 (Step S64).
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The compress:ing and restoring method of the image
in the second embodiment are modified as described below
to be applied to the case that the image data 150 does not
have any print dot:.
At first, the image data 150 is converted into the
binary format in the same way as the compressing and
restoring algorithm of the image in the second embodiment,
(Step S51). Moreover, the difference between the image
data 150 and the binary data 151 is calculated to thereby
generate the multi-valued data 152. At this time, the
print dot is not included in the picture indicated by the
multi-valued data 152.
In this case, after the dots are generated from the
picture indicated by the multi-valued data 152, the
multi-valued data 152 is compressed in accordance with the
print dot compressing algorithm. At first, the
graduation at each position of the picture represented by
the multi-valued data 152 is calculated. Moreover, at
each position of the picture, a dot having an area
proportional to the graduation at the position is
generated. On the basis of the positions and the areas
of the dots, the multi-valued data 152 is compressed in
accordance with the print dot compressing algorithm to
generate the print dot compression data module 154.
Moreover, it is integrated with the line picture
compression data module 155 to generate the collectively
compressed data module 156.
When the thus-generated collectively compressed
data module 156 is restored, the picture represented by
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the restored 'restoration image data 160 includes the dots
that are not included in the picture represented by the
original image data 150.
In this case, the print dot temporary data 157 may
be synthesized with the binary temporary data 158 after
conversion of the print dot temporary data 157
representative of the picture composed of the dots into
the picture temporary data that is not the picture composed
of the dots. The picture temporary data is generated as
follows. At first, the positions and areas included in
the print dot temporary data 157 is recognized. The
picture in which a region near the positions where the dots
exist is smeared at the graduation corresponding to the
area of the dots is generated. The data representative
of the picture is generated as the picture temporary data.
The original picture, which includes no dot, is
approximately restored in the restoration image data 160
generated from the binary temporary data 158 and the
thus-generated picture temporary data.
The restoration of the restoration image data 160
so as not to include the dots is effective for the case
that the occurrence of the moire is desired to be
protected.
In the compressing and restoring method of the image
data in this embodiment, the image data is classified into
the image element in the same way as the first embodiment .
Moreover, each image element is compressed and restored
in accordance with the algorithm corresponding to it.
This enables to improve the compression rate and to
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suppress of the deterioration in the picture quality
caused by the compression and restoration.
Moreover, in the compressing and restoring method
of the image data in this embodiment, the dots are
generated from the picture including no dots. Then, the
dot vectors are generated from the. dots. The redundancy
of the dots is effectively utilized. This enables to
improve the compression rate.
It should be note that the color image may be
compressed and restored by the compressing and restoring
method of the image data in this embodiment in the same
way as the first embodiment. In this case, the color image.
data representative of the color image is divided to
thereby generate the divided image data for each color in
the same way as the first embodiment. The compression and
restoration are performed on each of the divided image data
by the same method as the compression and restoring method
of the image data in this embodiment.
(EFFECT OF THE INVENTION)
The present invention provides the compression and
restoring method of the image data, in which the
deterioration in the picture quality caused by the
compression and the restoration is suppressed.
Also, the present invention provides the compression
and restoring method of the image data, in which the
compression rate is-large.
Also, the present invention provides the compression
and restoring method of the image data, in which the
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compression rate is large and the deterioration in the
picture quality caused by the compression of the image data
is suppressed.
Also, the present invention provides the compression
and restoring method of the image data, in which the image
data generated from the printed matter composed of the dots
is effectively compressed and restored.
Also, the present invention provides the compressing
method of the image data, in which the image data is
compressed at a high speed.
Also, the present invention provides the compressing
method of the image data, in which the image data
indicative of the picture whose edge is emphasized is
compressed at a high speed.
Also, the present invention provides the compression
and restoring method of the image data, which effectively
compresses and restores the image data generated from the
printed matter composed of the micro points having the
small areas, which do not have the arrangement defined by
the print rule.
Industrial Applicability
The present invention relates to a compressing
method and a restoring method of an image data.
