Note: Descriptions are shown in the official language in which they were submitted.
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"A method and apparatus for facilitating a determination of a
linear dimension of an object from an image of the object"
The present invention relates to a method and apparatus for facilitating a
determination of a linear dimension of an object from an image of the object,
and in
particular, though not limited to a linear dimension of an object from an
image of the
object formed by an image forming process, such as a photographic or
telephotographic process.
1o In many instances it is desirable to be able to determine one or more
dimensions of
an object by measuring an image of the object formed by a photographic or
telephotographic process or other imaging process, for example, it is
desirable that
by measuring an image in a photograph of an object one should be able to
determine the dimensions of the object.
There is therefore a need for a method and apparatus for facilitating a
determination
of a linear dimension of an object from an image of the object formed by a
photographic, telephotographic or other imaging process.
2o The present invention is directed towards providing such a method and
apparatus.
In this specification any and all references to magnification are intended to
include
reference to positive and negative magnification, in other words enlargement
in the
size of an object in image form and reduction in the size of an object in
image form.
According to the invention there is provided a method for facilitating a
determination
of a linear dimension of an objection from image of the object formed by an
image
forming process, wherein the method comprises the step of computing the
magnification of the image formed in an image plane of the image forming
process
3o relative to the object for facilitating the derivation of a measuring scale
for
subsequent reproduction along with a reproduction of the image, the
magnification of
the reproduced measuring scale corresponding to the magnification of the
reproduced image.
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In one embodiment of the invention the measuring scale is derived from the
computed value of the magnification of the image.
In another embodiment of the invention the measuring scale derived from the
computed value of magnification of the image is formed in the image plane
along
with the image.
In a further embodiment of the invention the computed value of the
magnification of
1o the image is stored. Preferably, the image is stored, and the stored
computed value
of the magnification of the image is stored separately from the stored image
but
correlated therewith.
In another embodiment of the invention the measuring scale is stored.
Preferably,
15 the measuring scale is stored separately from the stored image but
correlated
therewith.
Advantageously, the stored computed values of the magnification of the image
and
the measuring scale are stored electronically. Ideally, the stored computed
values of
2o the magnification of the image and the measuring scale are stored in
digital format.
In one embodiment of the invention the magnification of the image is computed
as a
function of the distance of the image plane from the optical centre of a lens
which
forms the image of the object, and the focal length of the lens.
In another embodiment of the invention the method further comprises the step
of
determining the distance of the image plane from an optical centre of the lens
which
forms the image of the object.
3o In a still further embodiment of the invention the method further comprises
the step
of determining the focal length of the lens.
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In one embodiment of the invention the magnification of the image is computed
under the R.P. Convention by dividing the distance of the image plane from the
optical centre of the lens by the focal length of the lens and subtracting the
value one
from the quotient of the division.
Alternatively, the magnification of the image is computed under the N.C.
Convention
by dividing the distance of the image plane from the optical centre of the
lens by the
focal length of the lens and subtracting the quotient of the division from the
value
one.
to
In one embodiment of the invention the distance of the image plane from the
optical
centre of the lens, and the focal length of the lens are determined by
electronic
computing. Alternatively, the distance of the image plane from the optical
centre of
the lens and the focal length of the lens are determined mechanically.
Preferably, the computation of the magnification of the image relative to the
object is
carried out by electronic computing.
In one embodiment of the invention the measuring scale is adapted to be formed
in
2o the image plane in a desired location relative to the image of the object.
In another embodiment of the invention the measuring scale is adapted to be
moveable in the image plane relative to the image.
In a further embodiment of the invention the measuring scale is formed
adjacent at
least one edge of an area of the image plane within which the image is formed.
Advantageously, a pair of measuring scales are formed adjacent a pair of
adjacent
edges of the area of the image plane within which the image is formed.
3o In a further embodiment of the invention the measuring scale is formed
around the
periphery of the area of the image plane within which the image is formed.
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In a still further embodiment of the invention the measuring scale is formed
adjacent
the image.
In one embodiment of the invention the measuring scale is formed by a
plurality of
spaced apart graduations. Preferably, the graduations of the measuring scale
are
equi-spaced apart.
Alternatively, the measuring scale is provided by a circle, the diameter of
which
corresponds to one or more measuring units. Preferably, the type and number of
to measuring units to which the diameter of the circle corresponds are
displayed along
with the circle. Advantageously, the type and number of measuring units to
which the
diameter of the circle corresponds are displayed within the circle.
Preferably, the
circle is bisected by a line corresponding to a diameter of the circle.
Advantageously,
the diameter line extends horizontally.
In one embodiment of the invention the measuring scale corresponds to the
metric
measuring system. Alternatively, the measuring scale corresponds to the
British
Imperial System.
2o In one embodiment of the invention the image and the measuring scale is
formed on
a receiving means in the image plane. Preferably, the receiving means
comprises a
photosensitive medium.
In another embodiment of the invention the receiving means comprises a charge
2s coupled device.
In another embodiment of the invention the measuring scale is formed by a
light
projecting means.
3o In a further embodiment of the invention the measuring scale is formed by a
light
masking means.
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In a further embodiment of the invention the measuring scale is formed by an
electronic forming means. Alternatively, the measuring scale is formed by a
mechanical forming means.
In a further embodiment of the invention the measuring scale is converted to
electronic signals, and preferably, in this embodiment of the invention the
image is
converted to electronic signals. Preferably, the electronic signals are
analogue
signals, and advantageously, the electronic signals are digital signals.
1o In one embodiment of the invention the image forming process is a
photographic
image forming process.
In another embodiment of the invention the image forming process is a
telephotographic image forming process.
In a still further embodiment of the invention the image forming process is a
video
forming process.
Additionally, the invention provides apparatus for facilitating a
determination of a
linear dimension of an object from an image of the object formed by an image
forming process wherein the apparatus comprises a computing means for
computing
the magnification of the image formed in an image plane of the image forming
process relative to the object for facilitating the derivation of a measuring
scale for
subsequent reproduction along with a reproduction of the image, the
magnification of
the measuring scale corresponding to the magnification of the reproduced
image.
In one embodiment of the invention a means is provided for deriving the
measuring
scale from the computed value of the magnification of the image.
3o In another embodiment of the invention a means for forming the measuring
scale
along with the image is provided.
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In one embodiment of the invention a magnification storing means is provided
for
storing the computed value of the magnification of the image.
In another embodiment of the invention a measuring scale storing means is
provided
for storing the measuring scale.
In a further embodiment of the invention an image storing means is provided
for
storing the image.
1o Preferably, the magnification storing means and the measuring scale storing
means
are separate from the image storing means but correlated with the image
storing
means.
In one embodiment of the invention a means for determining the distance of the
15 image plane from the optical centre of a lens which forms the image of the
object is
provided. Preferably, a means for determining the focal length of the lens is
provided.
In one embodiment of the invention the computing means computes the
2o magnification of the image from signals received from the means for
determining the
distance of the image plane from the optical centre of the lens and from
signals
received from the means for determining the focal length of the lens.
Preferably, the means for determining the distance of the image plane from the
25 optical centre of the lens comprises a first sensing means for sensing the
position of
the lens relative to the image plane. Advantageously, the first sensing means
is an
electronic sensing means. Alternatively, the first sensing means is a
mechanical
sensing means.
3o In another embodiment of the invention the first sensing means comprises a
combination of an electronic and a mechanical sensing means.
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In one embodiment of the invention the means for determining the focal length
of the
lens comprises an input means for facilitating inputting of the focal length
of the lens.
Preferably, the input means comprises a manual inputting means.
In another embodiment of the invention the means for determining the focal
length of
the lens comprises a second sensing means for sensing the focal length of the
lens.
Preferably, the second sensing means is an electronic sensing means.
Alternatively,
the second sensing means is a mechanical sensing means.
1o In another embodiment of the invention the second sensing means comprises a
reading means for reading a code on the lens indicating the focal length of
the lens.
In another embodiment of the invention a focal length storing means is
provided for
storing the focal length of the lens.
In a further embodiment of the invention the means for forming the measuring
scale
is adapted for forming the measuring scale in the image plane at a desired
location
relative to the image.
2o In one embodiment of the invention the means for forming the measuring
scale is
adapted for facilitating movement of the measuring scale in the image plane
relative
to the image.
In another embodiment of the invention the means for forming the measuring
scale
forms the measuring scale adjacent one edge of an area of the image plane
within
which the image is formed.
In a further embodiment of the invention the means for forming the measuring
scale
forms the measuring scale adjacent two adjacent edges of the area of the image
3o plane within which the image is formed.
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In one embodiment of the invention the means for forming the measuring scale
forms the measuring scale as a plurality of spaced apart graduations.
Preferably, the
graduations of the measuring scale are equi-spaced apart.
Alternatively, the means for forming the measuring scale forms the measuring
scale
in the form of a circle, the diameter of which corresponds to one or more
measuring
units. Preferably, the means for forming the measuring scale displays the type
and
number of measuring units to which the diameter of the circle correspond.
1o Advantageously, the type and number of measuring units to which the
diameter of
the circle corresponds is displayed within the circle. Advantageously, the
means for
forming the measuring scale forms a line corresponding to a diameter through
the
circle. Preferably, the line corresponding to the diameter of the circle
extends
horizontally across the circle.
In one embodiment of the invention the measuring scale corresponds to the
metric
measuring system. Advantageously, the measuring scale corresponds to the
British
Imperial Measuring System.
2o In one embodiment of the invention a receiving means is located in the
image plane
for receiving the image. Preferably, the receiving means comprises a
photosensitive
medium. Additionally or alternatively, the receiving means comprises a charge
coupled device.
In one embodiment of the invention the receiving means comprises a light
sensitive
photographic medium.
In another embodiment of the invention the means for forming the measuring
scale
is adapted for forming the measuring scale on the receiving means.
In a further embodiment of the invention the means for forming the measuring
scale
comprises a light projecting means for projecting light onto the receiving
means for
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forming the measuring scale thereon. Additionally or alternatively, the means
for
forming the measuring scale comprises a light masking means.
In another embodiment of the invention the means for forming the measuring
scale
comprises an electronic forming means for electronically forming the measuring
scale.
In a still further embodiment of the invention the means for forming the
measuring
scale comprises a printing means for printing the measuring scale on the
receiving
1o means.
Preferably, the magnification storing means, the image storing means and the
measuring scale storing means are provided by electronic storing means.
Advantageously, the magnification value of the image is stored in a digital
format in
the magnification storing means. Preferably, the measuring scale is stored in
a
digital format in the measuring scale storing means.
In one embodiment of the invention the apparatus is adapted for use in a
photographic camera.
In another embodiment of the invention the apparatus is adapted for use is a
telephotographic camera.
In a further embodiment of the invention the apparatus is adapted for use in a
video
camera.
In a still further embodiment of the invention the apparatus is adapted for
use in a
digital camera.
3o In a still further embodiment of the invention the apparatus is adapted for
incorporation into a photographic camera.
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In a still further embodiment of the invention the apparatus is adapted for
incorporation into a telephotographic camera.
In another embodiment of the invention the apparatus is adapted for
incorporation
into a video camera.
In a further embodiment of the invention the apparatus is adapted for
incorporation
into a digital camera.
1o Further the invention provides a camera comprising the apparatus according
to the
invention.
In one embodiment of the invention the camera is a photographic camera.
In another embodiment of the invention the camera is a telephotographic
camera.
In a further embodiment of the invention the camera is a video camera.
In a still further embodiment of the invention the camera is a digital camera.
The advantages of the invention are many. By virtue of the fact that a
measuring
scale is formed or provision is made for the subsequent formation of a
measuring
scale which can be subsequently reproduced with the image, and the fact that
the
measuring scale corresponds in magnification to the magnification of the image
or
any other subsequent reproduction of the image relative to the object, the
linear
dimensions of the image in the plane in which the image is formed can readily
easily
be determined by reference to the measuring scale, and the dimensions read
from
the measuring scale are the actual dimensions of the object. By forming the
measuring scale to correspond with the magnification of the image as the image
is
3o reproduced to different scales, the scale will correspondingly vary to
match the
varying magnification of the image.
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By projecting the measuring scale of a magnification corresponding to the
magnification of the image onto the receiving means, such as a photosensitive
medium, for example, a photosensitive photographic film, the film may be
developed
into a transparency or a photograph, and in-espective of the size to which the
photograph is printed the magnification of the measuring scale will always
correspond to the magnification of the image formed in the photograph. In
other
words, as the photograph is enlarged, thereby enlarging the image, the scale
is
proportionally enlarged, and vice versa. Furthermore, where the photographic
film is
developed onto a transparency, and the image on the transparency is projected
onto
1o a screen, as the projected image on the screen is enlarged or reduced, the
measuring scale is proportionally enlarged or reduced. Accordingly, the actual
linear
dimensions of the object in the plane of the image can readily easily be read
or
ascertained from the measuring scale.
15 A further advantage of the invention is achieved when the image is stored
electronically, as for example in the case of a telephotographic camera, such
as a
digital camera, video camera or the like, and when the magnification or
measuring
scale are similarly stored, since once the stored image of the object and its
magnification or the measuring scale are con-elated, as the image is
reproduced on
2o a larger or smaller scale, the magnification, and in turn the measuring
scale will be
automatically changed to correspond with the magnification of the image, and
thus,
by displaying the measuring scale along with the telephotographic image of the
object the linear dimensions of the object in the plane of the image can
readily easily
be read from the measuring scale, and the dimensions read from the measuring
25 scale are the actual dimensions of the object. The method and apparatus
according
to the invention are particularly advantageous where one wishes to determine
the
linear dimensions of a microscopic particle or organism an image of which can
be
recorded by an image forming process.
3o The invention will be more clearly understood from the following
description of some
preferred embodiments thereof which are given by way of example only with
reference to the accompanying drawings, in which:
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Fig. 1 is a schematic representation of a camera according to the invention
incorporating apparatus also according to the invention for forming a
measuring scale on a photosensitive medium,
Fig. 2 is a block representation of the apparatus for forming the measuring
scale of Fig. 1,
Fig. 3 is a plan view of a photographic film of the camera of Fig. 1,
1o Fig. 4 is a plan view of a photograph reproduced from the photographic film
of Fig. 3,
Fig. 5 is a plan view of an alternative photograph reproduced from a film of
the camera of Fig. 1,
Fig. 6 are alternative representations of scales which may be used in
connection with the photograph of Fig. 5, and indeed in connection with the
photograph of Fig. 4, and
2o Fig. 7 is a view similar to Fig. 1 of a digital camera also according to
the
invention.
Referring to the drawings and initially to Figs. 1 to 4 there is illustrated a
photographic camera according to the invention indicated generally by the
reference
numeral 1. The camera 1 is of the type which forms an image 2 of an object
(not
shown) on a receiving means, namely, a photosensitive photographic film 3 in
an
image forming plane 4 in the camera 1. The film 3 is subsequently removed from
the
camera 1 and developed to form the image 2. A photograph 7 may be reproduced
from the film 3 and/or a transparency for facilitating projection of an image
of the
3o transparency onto a screen. In Fig. 3 the photograph 7 is illustrated and
as can be
seen is an enlarged version of the film 3. The print of the image which is
indicated by
the reference numeral 8 in the photograph 7 is correspondingly magnified, in
other
words, enlarged relative to the image 2 on the film 3.
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The camera 1 incorporates apparatus also according to the invention indicated
generally by the reference numeral 10 for forming a measuring scale 12 along
with
the image 2 on the film 3 so that on printing the image of the film 3 onto the
photograph 7 a print of a measuring scale 14 which corresponds to the
measuring
scale 12 on the film 3 is reproduced. The measuring scales 12 and 14 are
metric
scales and the magnification of the measuring scales 12 and 14 correspond to
the
magnification of the images 2 and 8, respectively, relative to the object (not
shown),
so that the linear dimensions of the images 2 and 8 in the plane of the film 3
and
1o photograph 7, respectively, can readily easily be measured from the
measuring
scales 12 and 14, respectively, and these linear dimensions of the image are
the
actual dimensions of the object (not shown).
In this embodiment of the invention the measuring scale 12 formed on the film
3
15 comprises a plurality of graduations 15 which are equi-spaced along two
peripheral
edges 17 and 18 of the film 3. The graduations 15 are equi-spaced and
correspond
to units or a predetermined number of units of the metric system, depending on
the
magnification of the image 2, whether the magnification is positive or
negative or
zero. However, the spacing between the graduations 15 correspond to the
spacing
2o between the appropriate units or number of units on a metric scale
magnified to the
same level of magnification of the image 2 relative to the object. For
example, if the
image 2 has been positively magnified, in other words enlarged relative to the
object
by a factor of 5 and the spacing between adjacent graduations 15 of the
measuring
scale 12 is to corresponded to 1 mm of the object, then the actual spacing
between
25 each graduation of the measuring scale 12 on the film 3 would be 5mm.
Intermediate
graduations could be included between the graduations 15. Similarly, if the
image 2
had been negatively magnified, in other words reduced relative to the object
and, for
example, was reduced by a factor of 5, and the spacing between adjacent
graduations 15 of the measuring scale 12 is to correspond to 1cm of the
object, then
3o the actual spacing between the graduations 15 on the measuring scale 12
would be
'/5cm. Accordingly, as photographs 7 are produced from the film 3, as the
image 2 in
the photograph 7 is enlarged or reduced, the measuring scale 14 on the
photograph
7 is correspondingly enlarged or reduced. Thus, irrespective of the state of
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enlargement or reduction of the photograph relative to the film, and in tum
the
positive or negative magnification of the image relative to the object, by
reading the
linear dimensions of the image 8 in the plane of the photograph 7 the
corresponding
linear dimensions of the object are provided.
Turning now to the camera 1 and the apparatus 2, the camera 1 comprises a
housing 20. A lens 21 which forms the image 2 of the object (not shown) in the
image plane 4 on the film 3 is moveably mounted in the housing 20 for altering
the
distance between an optical centre 24 of the lens 21 and the image plane 4. In
this
1o embodiment of the invention the focal length of the lens 21 is fixed,
although, the
housing 20 is adapted for receiving lenses of different focal lengths and/or
combinations of lenses with variable/adjustable focal lengths. A drive means,
namely, a drive motor 25 is located within the housing 20 for driving the lens
21 in
the directions of the arrows A and B for varying the distance between the
optical
is centre 24 of the lens 21 and the image plane 4. A microprocessor 26 also
located in
the housing 20 controls the operation of the camera 1 and the drive motor 25
for
focusing the image 2 of the object (not shown) in the image plane 4. An
automatic
focusing device 27 which will be well known to those skilled in the art is
also located
in the housing 20 for detecting the location of the object. The microprocessor
26 in
2o response to signals received from the auto-focusing device 27 operates the
drive
motor 25 for moving the lens 21 for in turn focusing the image 2 of the object
(not
shown) in the image plane 4.
In this embodiment of the invention the apparatus 10 shares the microprocessor
26
2s with the camera 1, although, it will be appreciated that the apparatus 10
may be
provided with a separate microprocessor, which would communicate with the
microprocessor controlling the camera 1. This would particularly be the case
in the
event of the apparatus 10 being retro-fitted to the camera 1.
3o A means for determining the distance between the optical centre 24 of the
lens 21
and the image plane 4 comprises a first sensor 30 which senses the position of
the
lens 21, and in turn its optical centre 24 relative to the image plane 4. A
means for
determining the focal length of the lens 21 comprises a second sensor 32 which
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senses the type of lens 21 fitted into the camera 1, and thus the focal length
of the
lens 21 can be determined by the microprocessor 26 from a look-up table stored
in
the microprocessor 26. The second sensor 32 is provided with a reading means
for
reading a code on the lens which identifies the lens type. The microprocessor
26 is
5 programmed using suitable code for computing from the signals received from
the
first sensor 30 the distance between the optical centre 24 of the lens 21 and
the
image plane 4, and is also programmed using suitable code for computing the
magnification of the image 2 of the object formed in the image plane 4 on the
film 3
relative to the object.
l0
In this embodiment of the invention the magnification of the image 2 relative
to the
object is derived in accordance with the R.P. Convention from the formula:
M=V/F-1
where M = magnification,
15 V = distance of the optical centre 24 of the lens 21 from the image
plane 4, and
F = focal length of the lens 21.
Alternatively, the magnification of the image 2 formed in the image plane 4 on
the
2o film 3 relative to the object (not shown) may be derived from the following
formula
using the N.C. Convention:
M=1-V/F
where V = distance of the optical centre 24 of the lens 21 from the image
plane 4, and
F = focal length of the lens 21.
A means for deriving the measuring scale 12 to be projected onto the film 3 in
the
image plane 4 comprises suitable code in the microprocessor 26 which computes
the measuring scale 12 from the computed value of the magnification of the
image.
3o A means for forming the measuring scale 12 on the film 3 comprises a light
projecting means, namely, a light projector 35 which under the control of the
microprocessor 26 projects short lines of light onto the film 3 in the image
plane 4 for
forming the graduations 15 of the measuring scale 12 adjacent the peripheral
edges
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17 and 18 of the film 3. The short lines of light are projected for forming
the
graduations 15 of the measuring scale 12 spaced apart the appropriate distance
from each other corresponding to the number of metric units between the
graduations 15 and the magnification of the image 2 relative to the object
(not
shown). Such light projectors as the light projector 35 will be well known to
those
skilled in the art, and are typically of the type used for printing a date or
time onto a
film in a camera.
Accordingly, when the film 3 is developed, and the image of the film is
subsequently
to printed onto photographic paper or onto a transparency the image 2 is
formed as a
printed image 8 on the photograph 7, and the measuring scale 12 is printed as
the
measuring scale 14 on photograph 7. As discussed above as the image of the
film 3
is enlarged or reduced, as the case may be in a printing process onto a
photographic
paper or onto a transparency the image 8 and the measuring scale 14 are
15 correspondingly enlarged or reduced as the case may be.
Referring now to Figs. 5 and 6 there is illustrated a film 40 of an image 41
of an
object (not shown) which has been formed in a camera (not shown) also
according
to the invention. The camera according to this embodiment of the invention is
2o identical to the camera 1 with the exception that the light projector 35
instead of
projecting a scale of graduations as in the case of the camera 1 of the Figs.
1 to 4,
projects a measuring scale in the form of a diameter 42 of a circle 43. The
diameter
42 of the circle 43 represents a number of units in the metric system
corresponding
to the magnification of the image 41 relative to the object (not shown). In
this
25 embodiment of the invention the length of the diameter 42 represents 10cm,
and the
number of units, namely, the numeral "10" is displayed within the circle 43
above the
diameter 42 and the type of units, namely, "cms" is displayed beneath the
diameter
42 within the circle 43. The type and number of units which is represented by
the
diameter 42 of the circle 43 is relayed by the microprocessor to the light
projector 35
3o for projecting along with the circle 43 and diameter 42 onto the film 3 in
the image
plane 4. In this embodiment of the invention the circle 43 is located towards
the
lower right hand corner of the film 3, although, it will be readily
appreciated that the
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circle 43 may be located in any desired position on the film by appropriately
directing
the light projector 35 onto the film 3 in the image plane 4.
Referring now in particular to Fig. 5 alternative arrangements of measuring
scales
according to the invention provided by circles 43 as well as the type and
number of
units represented by the length of the diameter of the circles 43 are
illustrated.
Referring now to Fig. 7 there is illustrated a camera; in this embodiment of
the
invention a telephotographic camera, namely, a digital camera also according
to the
1o invention and indicated generally by the reference numeral 50. The digital
camera 50
incorporates apparatus also according to the invention indicated generally by
the
reference numeral 51 for deriving and storing a measuring scale of an image
formed
by the camera 50. Although a digital camera 50, the main components of the
camera
50 are substantially similar to those of the camera 1, as are the main
components of
15 the apparatus 51 substantially similar to those of the apparatus 10, and
similar
components are identified by the same reference numerals. In this embodiment
of
the invention the camera 50 comprises a housing 20, a lens 21 located in the
housing 20 and moveably mounted relative to the housing 20 for varying the
distance between the optical centre 24 of the lens 21 and the image plane 4 of
the
2o camera 20. Instead of a film 3 a photosensitive medium, namely, a charge
coupled
device 52 is located in the image plane 4 for receiving the image. Light
through the
lens 21 before being focused on the charge coupled device 52 is split by
defraction
through a prism (not shown) or other suitable splitting means into the primary
colours
of red, green and blue, which are then directed onto the charge coupled device
52.
25 Analogue signals of the image of the object formed on the charge coupled
device 52
are relayed to an analogue-to-digital converter 54, and in turn the digital
signals of
the image from the analogue-to-digital converter 54 are read by the
microprocessor
26 for encoding for forming a digital representation of the image. The digital
image is
in turn stored by the microprocessor 26 in a suitable image storing means,
which
3o typically is a memory card or disc 56.
The auto-focusing device 27 in conjunction with the microprocessor 26 and the
drive
motor 25 moves the lens 21 relative to the image plane 4 for focusing the
image of
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the object on the charge coupled device 52 in the image plane 4 as already
described with reference to Fig. 1. The distance between the optical centre 24
of the
lens 21 and the image plane 4 and the focal length of the lens 21 are
determined by
the microprocessor 26 from signals received from the first and second sensors
30
and 32, respectively, as already described with reference to the camera 1 and
the
apparatus 10 of Figs. 1 to 4. The microprocessor 26 similarly determines the
magnification of the image formed in the image plane 4 on the charge coupled
device 52 and in turn derives a measuring scale as already described.
1o The measuring scale is stored in a measuring scale storing means, which is
also
provided by the memory card or disc 56, and preferably is stored in a location
on the
memory card or disc 56 separate from the location at which the image is stored
on
the memory card or disc 56. If desired the magnification of the image may also
be
stored in a magnification storing means, which is also provided by the memory
card
15 or disc 56, and preferably, is stored in a location on the memory card or
disc 56
separate from the stored image and the stored measuring scale.
Accordingly, when an image is being reproduced from the memory card or disc 56
the measuring scale can be separately retrieved from the memory card or disc
56
2o and moved to any desired location relative to the image, and indeed, the
orientation
of the measuring scale may also be varied relative to the image for
facilitating direct
measuring of the image by placing the measuring scale across the image between
the points of the image, across which the linear distance is to be determined.
The
measuring scale and image will be stored so that as the image is enlarged on
25 reproduction the measuring scale is correspondingly enlarged and
reproduced.
While it is not essential, the storing of the magnification value of the image
would
facilitate enlargement or reduction of the measuring scale to correspond with
enlargement or reduction of the image.
3o While the components of the digital camera 50 for forming the digital image
on the
memory card or disc 56 have not been described in detail, digital cameras, and
the
formation of a digital image will be well known to those skilled in the art.
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19
A further advantage of storing the image and the measuring scale and/or the
magnification of the image separately from each other is that the image if
desired
could be displayed without the measuring scale. Furthermore, separate storage
would also facilitate independent operation of the measuring scale, for
example,
movement of the measuring scale would be facilitated so that the measuring
scale
could be moved to any part of the image for determining the dimensions between
any two points on the image, which in turn would give the actual distance of
the two
points on the object of which the image is formed. It is also envisaged that a
menu of
different types of measuring scale could be provided and one could select a
specific
to type of measuring scale. Accordingly, by separately storing the image and
the
magnification of the image a selected measuring scale could then be prepared
electronically from the value of magnification of the image. Thus, by
separately
storing the image and the measuring scale and/or the magnification the image
and
type of measuring scale and its position could be determined when a print is
being
made of the image, or when the image is being viewed. As discussed above the
measuring scale could be moved relative to the image during viewing.
Additionally, in a digital or video camera the measuring scale could be
selected and
programmed to appear during specific frames only, and in cases where the
2o magnification of the image remains constant throughout a sequence of
frames,
recalculation of the magnification and/or the measuring scale would be
avoided.
While two methods for determining the magnification of the image have been
described, it is also envisaged that the magnification may be computed by the
microprocessor using the following formula:
M = V/U
where M = magnification,
V = distance from the optical centre 24 of the lens 21 from the image
plane 4, and
3o U = distance of the object from the optical centre 24 of the lens 21.
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In determining the magnification using this formula, the value of "U" would be
determined by the microprocessor 26 of the apparatus 10 and 51 from signals
received from the auto-focusing device 27.
While various types of measuring scales have been described, it will be
readily
apparent to those skilled in the art that any other suitable measuring scales
may be
provided. It will also of course be appreciated that the measuring scales may
be
formed in any other suitable location on the film, for example, it is
envisaged that the
measuring scales may be provided on X and Y axis which would bisect the film
1o vertically and horizontally.
While the apparatus according to the invention has been described for use in a
photographic camera and in a digital camera, it will be readily apparent to
those
skilled in the art that the apparatus according to the invention could be used
in any
15 other type of photographic or telephotographic camera, for example, in a
video
camera, a video camcorder, or in any other such image forming device,
apparatus or
process.
