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Patent 2185753 Summary

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(12) Patent: (11) CA 2185753
(54) English Title: DIGITAL IMAGE DECODING APPARATUS
(54) French Title: DISPOSITIF DE DECODAGE D'IMAGES NUMERIQUES
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • G06T 9/00 (2006.01)
  • H04N 7/50 (2006.01)
  • H04N 7/26 (2006.01)
  • H04N 7/46 (2006.01)
(72) Inventors :
  • OHIRA, HIDEO (Japan)
  • MURAKAMI, TOKUMICHI (Japan)
  • ASAI, KOHTARO (Japan)
  • SHIMADA, TOSHIAKI (Japan)
(73) Owners :
  • MITSUBISHI DENKI KABUSHIKI KAISHA (Japan)
(71) Applicants :
  • MITSUBISHI DENKI KABUSHIKI KAISHA (Japan)
(74) Agent: GOWLING WLG (CANADA) LLP
(74) Associate agent:
(45) Issued: 2000-09-12
(22) Filed Date: 1996-09-17
(41) Open to Public Inspection: 1998-03-18
Examination requested: 1996-09-17
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data: None

Abstracts

English Abstract




Data decoded by a decoding section (101) are compressed by
a compressing section (102) and then stored in a
forecast/display frame memory section (103). The data in the
forecast/display frame memory section (103) which are required
to decode the other frames in the decoding section (101) are
expanded and supplied to the decoding section through an
expanding A section (104). The decoding section (101) uses
the data restored by the expanding operation to decode the
image data subjected to the forecast encoding operation. On
the other hand, the display frame is subjected to the
expanding operation at an expanding B section (105) after it
has been read out from the forecast/display frame memory
section (103), the expanded display frame then being output
and supplied to a display device. Thus, the data stored in
the forecast/display frame memory section (103) can be
compressed to reduce the size of memory capacity.


French Abstract

Les données décodées par la section de décodage (101) sont comprimées par une section de compression (102) puis stockées dans une section de la mémoire pour les trames anticipées/affichées (103). Les données stockées dans la section de la mémoire pour les trames anticipées/affichées (103) qui sont nécessaires pour décoder les autres trames dans la section de décodage (101) subissent une expansion et sont envoyées à la section de décodage par une section d'expansion A (104). La section de décodage (101) utilise les données restaurées par l'opération d'expansion pour décoder les données sur les images soumises à l'opération d'encodage d'anticipation. D'un autre côté, la trame d'affichage subit une opération d'expansion dans une section d'expansion B (105) après avoir été lue à partir de la section de la mémoire pour les trames anticipées/affichées (103), la trame d'affichage ayant subi une expansion est alors produite et envoyée à un dispositif d'affichage. De cette façon, les données stockées dans la section de mémoire pour les trames anticipées/affichées (103) peuvent être comprimées afin de réduire la taille de la capacité de mémoire.

Claims

Note: Claims are shown in the official language in which they were submitted.




Claims:

1. A digital image decoding apparatus comprising:
a decoding section for decoding inter-block image encoded
data in block units to form decoded data;
a compressing section for compressing the
decoded-in-block-unit data from said decoding section in block
unit to form compressed data;
a forecast frame memory section for holding the
compressed-in-block-unit data from said compressing section
which correspond to one or more image frames; and
an expanding section for supplying data required by the
decoding operation at said decoding section to said decoding
section, said expanding section being operative to read out
the compressed data from said forecast frame memory section,
the read compressed data being then expanded and supplied to
said decoding section.

2. A digital image decoding apparatus as defined in claim 1
wherein said decoding section is operative to decode encoded
dynamic image data sequentially in block units and wherein
said compressing section is operative to completely compress
the decoded-in-block-unit dynamic image data from said decoding
section within a time shorter than the decoding time.

3. A digital image decoding apparatus as defined in claim 1,
further comprising a display frame memory section for holding one or



22



more image display frames used only to display the data
supplied from said compressing section.

4. A digital image decoding apparatus as defined in claim 3
wherein said compressing section is operative to compress at
least the data of a forecast frame to be written in said
forecast frame memory or the data of a display frame to be
written into said display frame memory.

5. A digital image decoding apparatus as defined in claim 3
wherein said compressing section is operative to compress both
the data of a forecast frame to be written in said forecast
frame memory and the data of a display frame to be written
into said display frame memory.

6. A digital image decoding apparatus as defined in claim 3
wherein the data input into said decoding section are
inter-frame encoded data and wherein said compressing section
is operative not to compress the inter-frame encoded data if
they are of the unidirectional forecast type from the forward
direction and operative to compress the inter-frame encoded
data if they are of the bidirectional forecast type from the
forward and backward directions.

7. A digital image decoding apparatus as defined in claim 1
wherein said decoding section is operative to output an
encoded data having pixels each of a bit length equal to t


23



(which is a natural number), said pixels being included in
blocks each of which is formed by M (=2m) pixels X N (=2n)
lines (in which m and n are natural numbers) and wherein said
compressing section is operative to allocate more bit length
to important converted coefficients and to allocate less bit
length to less important coefficients.

8. A digital image decoding apparatus as defined in claim 7
wherein said compressing section is operative to encode the
number of bits generated after one block has been converted
into a fixed length equal to S bits (S<M X N X t).

9. A digital image decoding apparatus as defined in claim 1,
further comprising a forecast frame expanding section for
reading out the compressed data for one or more blocks which
include the data of the block of P pixels X Q lines at a given
location from said forecast frame memory when the block data
determined by P (=2p) pixels X Q (=2q) lines (in which p and q
are natural numbers) in the forecast frame stored in the
forecast frame memory of said decoding section at said given
location are required, the read compressed data then being
expanded with the necessary block data of P pixels X Q lines
being extracted therefrom and supplied to said decoding section.

10. A digital image decoding apparatus as defined in claim
9 wherein said forecast frame expanding section includes a
block memory for expanding and storing the compressed


24



in-block-unit data read out from the forecast frame memory by
a plurality of blocks and wherein, if new block data is
required by the decoding operation, said block memory is
updated for each block.

11. A digital image decoding apparatus as defined in claim
9 wherein the processing speed in said forecast frame
expanding section is sufficiently higher than that of said
decoding section, thereby eliminating a time loss in the
decoding operation for encoded dynamic image data.

12. A digital image decoding apparatus as defined in claim
3, further comprising a display expanding section for reading
out the compressed data stored in said display frame memory in
block unit, expanding the read out data and sequentially
outputting the expanded data in the horizontal image frame
scan direction.

13. A digital image decoding apparatus as defined in claim
12 wherein said display expanding section has a display memory
for storing the expanded data for each block in the horizontal
image frame width direction, whereby the data can be read out
from said display memory depending on the image display scan
line.

25

Description

Note: Descriptions are shown in the official language in which they were submitted.


2 1 85~53
-
TITLE OF THE lNv~NlION
Digital Image Decoding Apparatus
BACKGROUND OF THE lNV~N'l'ION
Field of the Invention:
The present invention relates to a digital image decoding
apparatus and particularly to such an apparatus which is
suitable for use in digital CATV, digital broadcasting
systems, and so on.
Description of the Prior Art:
Figs. 16 and 17 show the block diagram and external
memory map of an image processing LSI (e.g., STi3500) which
are described in the manual issued by SGS-Thomson
Microelectronics.
In Fig. 16, reference numeral 501 denotes a micon
interface; 502 an FIFO memory; 503 a start code detecting
section; 504 a memory I/O unit; 505 a variable-length
decoding section; 506 a decode processing section; 507 a
display processing section; 508 an external memory; 550 a
micon interface line; 551 a micon bus; 552 data lines; 553
data lines; 554 an external memory bus; and 555 an
input/output line.
In Fig. 17, reference numeral 601 denotes a bit buffer
area; 602 an OSD (on-screen display) area; 603 a forecast
frame memory 1 area; 604 a forecast frame memory 2 area; and
605 a display frame memory area.
The operation thereof will now be described. Encoded
data accumulated in the bit buffer area 601 of the external


~ 2185753

memory 508 is fed to the start code detecting section 504
through the external memory bus 554 wherein the start code of
the encoded data is detected. After the start code has been
detected, the encoded data portion following the start code
is supplied to the variable-length decoding section 505
through the FIFO memory 502, wherein the encoded data portion
is subjected to variable-length decoding. The
variable-length decoded data is then processed and subjected
to image decoding by the decode processing section 506. The
decoded image is written into the external memory 508 through
the memory I/O unit 504.
The external memory 508 has the forecast frame memory 1
area 603, the forecast frame memory 2 area 604 and the
display frame memory area 605, in each of which the decoded
images will be stored. Image data used to forecast the other
frames is written into the forecast frame memory 1 area 603
or the forecast frame memory 2 area 604. Image data used
only for the display is written into the display frame memory
area 605.
The data written into the display frame memory area 605
is then read out from there in synchronism with signals such
as the horizontal/vertical synchronizing signals in TV scenes
and output to the display processing section 507 through the
external memory bus 554.
Data, such as character data, to be displayed in the OSD
(on-screen display) area 602 of the external memory 508 is
accessed, if necessary, as in the display frame memory area


2 1 85753

605 and then supplied to the display processing section 507
through the external memory bus 554. If the data in the OSD
area 602 is valid, the display processing section 507
overlays that valid data on the data read out from the
display frame memory area 605 and externally outputs the
overlaid data.
In such a manner, there can be provided a displayed image
on the display data that has been stored in the external
memory 508.
In the aforementioned digital image decoding apparatus of
the prior art, the external memory 508 must store all the
data required by the decoding step. More particularly, if
data is to be encoded spanning between adjacent frames, all
the data of other frames used to encode one frame have to be
stored in the external memory 508 for decoding the image data
of that frame.
Therefore, the decoding step requires a huge data
storage. This raises a problem in that the required capacity
of the external memory 508 is increased, enlarging the
hardware.



SUMMARY OF THE lhV~NlION
In order to overcome the problem mentioned above, an
object of the present invention is to provide a digital image
decoding apparatus which can realize the reduction of
hardware by suppressing memory size as much as possible.
According to the present invention, the data is


' 2185753

compressed by a compressing section after it has been
decoded. Therefore, data hold by the forecast frame memory
section are those compressed by the compressing section.
Thus, the required capacity of the forecast frame memory
section is reduced. This enables reduction of the
addressing, reading, and writing data width in this memory,
resulting in reduction of the overall system size. This can
also facilitate the hardware of the digital decoding
apparatus and further accomplish the high-speed operation
thereof. Consequently, dynamic image data can be more
effectively processed by the digital decoding apparatus of
the present invention.
In one form of the present invention, the compressing
section can perform the compression for a time shorter than
that required by the decoding section. Therefore, the
operation of the compressing section will not adversely
affect the decoding operation for incoming dynamic images and
the displaying operation for decoded image data.
In another form of the present invention, the display
frame data only used for display is stored in a memory other
than the forecast memory that is used to decode the other
frames. Thus, the forecast and display frames can be more
easily read out.
In a further form of the present invention, at least one
set of forecast frame data to be written into the forecast
frame memory and the display frame data to be written into
the display frame memory is compressed by the compressing



21 8~753

section, depending on the type of image frame. Thus, the
required capacity of the display frame is less then when the
compression is performed for the display frame. On the other
hand, the transmission to any other frame of degraded
compressed image data in a forecast frame can be prevented
when compression is not performed for that forecast frame.
This is particularly effective for cases when compression is
made through an irreversible encoding system.
In a further form of the present invention, the
compressing section compresses both the forecast and display
frames. Compression for decoded image data can therefore be
efficiently carried out, resulting in reduction of both the
forecast and display frame memory capacities. This is
particularly preferable for compression through an
irreversible encoding system since the compressed data can be
perfectly restored through expansion.
In a further form of the present invention, all the data
can be held in the forecast frame memory without being
compressed if they are to be unidirectionally forecasted. On
the other hand, all the data can be held in the forecast
frame memory while being compressed if they are to be
bidirectionally forecasted. Therefore, the train of encoded
data through the unidirection forecast can be decoded without
degradation of the image quality.
There is also a case where it is preferred that depending
on the type of image frame, the data to be written into the
forecast frame memory is compressed while the other data to


21 85753

be written into the display frame memory is not compressed.
This can also reduce the capacity of the frame memory in
which the decoded data is stored.
In a further form of the present invention, the
compressing section can use Harr conversion to divide a
converted coefficient into an important coefficient and a
less important coefficient. An increased number of bits can
be assigned to an important coefficient, resulting in more
efficient compression.
In a further form of the present invention, the amount of
information bits S generated for each block to be compressed
can be fixed. Therefore, a location of the frame memory in
which each block is to be stored can easily be grasped. This
simplifies an addressing structure and facilitates removal of
any block data.
In a further form of the present invention, an expanding
section for the forecast frame reads data required by the
decoding section from the forecast frame memory in which the
data have been stored in block units. The read and
compressed data is expanded and the data at a desired
location is output. Thus, any data required by the decoding
section can be taken out. This can provide a desired
decoding operation in the decoding section.
In a further form of the present invention, the data
expanded in block unit can be accumulated in a block memory
such that a forecast image data required by the decoding
operation can be efficiently retrieved from any location in



2 l gs7~3

the block memory.
In a further form of the present invention, the
processing speed in the compressing and forecast frame
expanding sections can be increased higher than that in the
decoding section. Thus, dynamic images sequentially supplied
to these sections can be processed in real time. In a
further form of the present invention, the display frame data
compressed in block unit are read out and expanded while the
expanded image data are sequentially outputted in the scan
direction (in synchronism with the horizontal and vertical
scans for image display). Thus, the data for image display
can be obtained.
In a further form of the present invention, the display
expanding section has a display memory for storing image data
for one frame. Thus, the data read out from the display
memory can be directly used as display signals.
AS described, the digital image decoding apparatus of the
present invention can not only reduce the capacity of a frame
memory required when the decoded data is used to perform the
decoding and displaying operations for any other frame, but
also decrease the address and data width required when the
reading and writing operations are made for the frame memory.
This can greatly reduce the apparatus in size and cost.



25BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram of one embodiment of a digital

image decoding apparatus constructed in accordance with the





2 1 85753

present invention.
Fig. 2 is a view showing different types of frames.
Fig. 3 is a bit map of a frame memory.
Fig. 4 is a flow chart showing a compressing process.
Fig. 5 is a flow chart showing another compressing
process.
Fig. 6 is a view illustrating a quantization.
Fig. 7 is a bit map of a forecast/display frame memory
section.
Fig. 8 is a view showing Harr conversion which is one of
the compressing systems.
Fig. 9 is a view showing a data area required by the
expansion and a data area to be decoded.
Fig. 10 is a block diagram of an expanding A section.
Fig. 11 is a view showing the structure of an expanding B
section.
Fig. 12 is a view illustrating the process of the
expanding B section.
Fig. 13 is a view showing different types of encoded
trains.
Fig. 14 is a flow chart illustrating the compressing
operation.
Fig. 15 is a schematic bit map of a forecast frame
memory.
Fig. 16 is a block diagram of a digital image decoding
apparatus constructed in accordance with the prior art.
Fig. 17 is a bit map of the prior art frame memory.


- 21 85753

DE~ATT~ DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be described by way of
example with reference to the drawings.
Fig. 1 is a schematic block diagram of one embodiment of
a digital image decoding apparatus according to the present
invention. Referring to Fig. 1, reference numeral 101
designates a decoding section for decoding encoded image
data; 102 a compressing section for compressing the decoded
data; 103 a frame memory section comprising a forecast frame
memory and a display frame memory; 104 an expanding A section
for expanding the compressed data read out from the frame
memory; and 105 an expanding B section for outputting the
data in the order of raster.
Reference numeral 150 represents encoded data; 151
decoded data; 152 compressed data; 153 compressed data; 154
display data; and 155 expanded data.
The operation of the apparatus shown in Fig. 1 will be
described below. The decoding section 101 decodes an
incoming encoded data using the expanding data 151 as
forecast data. The decoded data 151 is then reversibly or
irreversibly compressed by the compressing section 102 to
reduce the amount of information therein. The compressed
data 152 is used as a forecast data for a frame to be decoded
in future and also written into the forecast/display frame
memory section 103 for displaying. The compressed data of a
frame not used for forecasting is written into the display
frame area while the compressed data of a frame used for



2 1 85753

forecasting is written into both the display and forecast
frame areas. All the data are not necessarily compressed, as
will be described.
The written compressed data is expanded by the expanding
B section 105 for image display. The expanded data is read
out and displayed in the order of raster.
On the other hand, the expanding A section 104 accesses
the forecast/display frame memory section 103. The resulting
compressed data is then expanded and supplied to the decoding
section 101 as an expanded data 155 (forecast data) that is
required by the decoding operation in the decoding section
101 .
The forecast/display frame memory section 103 may be
structured to have a capacity less than the amount of
information that is possessed by an image data to be
displayed, since the frame memory section 103 is adapted to
store the compressed data.
Referring now to Fig. 2, reference numeral 301 denotes a
forecast frame used to decode the other image frame; and 302
a display frame only used to display the image. Referring
further to Fig. 3, reference numeral 310a designates a
forecast frame memory area for storing a first forecast
frame; 310b a forecast frame memory area for storing a second
forecast frame; and 311 a display frame memory area for
storing a display frame.
The forecast frame 301 is stored in the forecast frame
memory area 310 (310a and 310b) and also used to decode the



2 1 85753

other forecast frame and further utilized to decode the
display frame 302. On the other hand, the display frame 302
is stored in the display frame memory area 311 of the
forecast/display frame memory section 103 and only used for
displaying.
In such a manner, the data of the display frame is only
used for displaying. Even if any error is generated when the
data is compressed by the compressing section 102 of Fig. 1
through the irreversible compression system, such an error
will not be transmitted to the other frame since it does not
refer to the display frame 302.
On the other hand, the data of the forecast frame written
in the forecast frame memory area 310 is used to decode the
other image frame. Thus, when the forecast frame 301 is
compressed through the irreversible compression system, any
error generated by such a compression will be transmitted to
the other image frame. With use of the irreversible
compression system, the compression is not performed for the
forecast frame 301 while the data is accumulated in the
forecast frame memory area 310. Therefore, transmission of
the error generated by the compression to the other frame
will be prevented.
On the other hand, when the compression is to be made in
the compressing section 102 through the reversible
compression system, the compressed data can be perfectly
restored. Therefore, the compression is performed for both
the forecast and display frames 301, 302. This reduces the
11


2185753

amount of information.
Fig. 4 is a flow chart showing a compression procedure.
It is first judged whether the decoded image frame outputted
from the decoding section 101 is a forecast or display frame
data. If the data is the forecast frame data, it will be
written into the forecast frame memory area 310 of the
forecast/display frame memory section 103 without being
compressed. On the other hand, the display frame data is
written into the display frame memory area 311 of the
forecast/display frame memory section 103 while being
compressed. Such a procedure is preferable when the
compression will not affect the other frame and if the
compressing section 102 takes the irreversible compression
system.
When the compression is performed through the reversible
system as shown in Fig. 5, both the forecast and display
frame data are compressed. The forecast frame data is
written into both the forecast and display frame areas 310
and 311 while the display frame data is written into the
display frame memory area 311.
Depending on the type of image frame there is a further
case where it is preferable that only the forecast frame data
be compressed.
Fig. 6 schematically shows the procedure of a compression
process. Data in blocks of M pixels XM lines that have been
decoded at the decoding section 101 of Fig. 1 are subjected
to a given conversion. Since each of the pixels is
12


2 1 85753

represented by bits equal in number to t, the amount of
information in these blocks is equal to MXMXt. After the
data of M pixelsXM lines have been subjected to a conversion
such as discrete cosine or other conversion, they will
include low-frequency signals on the left and upper region,
intermediate-frequency signals on the center region and
high-frequency signals on the right and lower region.
Fig. 7 is a memory map of data for one frame compressed
at the forecast/display frame memory section 103. In this
figure, reference numeral 210 denotes a location in which the
information of one compressed frame is stored; and 211 a
location in which the information of the t-th block in one
compressed frame is stored.
The compressing section 102 converts the blocks 201 of
MXM pixels depending on the characteristics of the image.
The converted blocks are divided into a low-frequency signal
region 202, an intermediate-frequency signal region 203 and a
high-frequency signal region 204. The allocation is
performed such that the number of pixels in the low-frequency
signal region is equal to rl and the allocated number of bits
in the low-frequency signal region is equal to sl bits/pixel;
the number of pixels in the intermediate-frequency signal
region is equal to r2 and the allocated number of bits in the
intermediate-frequency signal region is equal to s2
bits/pixel; and the number of pixels in the high-frequency
signal region is equal to r3 and the allocated number of bits
in the low-frequency signal region is equal to s3 bits/pixel

13

2 1 ~57~3
-



(and, however, sl~s2>s3; rl+r2+r3=MXM). The allocation of a
larger number of bits to a lower-frequency region is because
the signals in the lower-frequency region more greatly affect
the image. Thus, the affection to the image can be reduced
while the amount of data can be compressed and reduced in
size.
If a quantization is performed after such an allocation
of the bit number has been carried out, an amount of
information S generated in the blocks:
S=rlXSl+r2XS2+r3XS3
will always be maintained constant.
Therefore, the addressing in block unit can be regularly
requested and a desired image frame compressed and
accumulated in a memory can be read out from any block. If
it is assumed, for example, that a head address in a
compressed frame is A as shown in Fig. 7, the address of the
t-th block in the compressed frame is between (A+(t-1)XS)
and (A+tXS-l). If the t-th block is to be accessed for
decoding, any block can be easily accessed since the memory
location of any compressed frame is known.
Fig. 8 shows a case where Harr conversion, which is one
type of irreversible conversion, is used as a
converting/encoding algorithm. In this figure, A shows a
coefficient matrix for eight pixelsXeight lines to be
converted.
If it is assumed that an image of a block before it is
subjected to one-dimensional Harr conversion is X and the
14


2 1 857~3

converted block is B,
B--AX.
If the block B becomes B' after it has been quantized and
compressed, a block Y obtained after the block B' has been
expanded is

Y=A-lB
The compression and expansion can be carried out through such
an operation.
Such a process is an irreversible compression since the
number of bits is reduced through the quantization after
conversion. It is to be understood that the present
invention is not limited to Harr conversion, but may be
similarly applied to any other conversion.
Fig. 9 shows the relationship between different areas in
a one-frame image data. In this figure, reference numeral
220 denotes an image frame; 221 a decoded forecast block
including pXQ pixels required by the decoding operation; and
222 a group of expanding blocks required by the expanding
operation.
Referring to Fig. 9 as well as Fig. 1, the decoding
section 101 uses the decoded forecast block 221 of pXQ
pixels which is obtained from any point in the image frame
220 decoded as a forecasting image data and accumulated in
the forecast/display frame memory section 103. On the other
hand, the data within the forecast/display frame memory
section 103 are compressed and stored in block units. Thus,
where the encoded forecast block 221 of pXQ pixels spans



2 1 85753

between adjacent blocks, the necessary data will not be
obtained by expanding only one block.
To overcome such a problem, the expanding A section 104
takes out groups of expanding blocks 222 containing the
decoded forecast block 221 from the forecast/display frame
memory section 103. The expansion is performed for each
block. The expanding A section 104 then extracts the data of
the decoded forecast block 221 required by the decoding
section 101, this data being fed to the decoding section 101.
Where the expanding A section 104 takes out the compressed
data from the forecast/display frame memory section 103, the
address of the compressed data within the forecast/display
frame memory will be subjected to the aforementioned
addressing.
In such a manner, the data of the decoded forecast block
can be obtained from any area in the stored data. By
accumulating the data of the groups of expanding blocks 222
in an expanded data block memory (not shown) within the
expanding A section 104, the forecast image data required
when the decoding section 101 is to decode the next block is
provided only by updating a new necessary part.
Particularly, the location of the decoded forecast block
required by the decoding operation is forecasted on motion
vectors between the frames and therefore more probably
re-used between the adjacent blocks. Thus, a predetermined
number of expanded blocks have been stored in the expanding A
section 104. When the next block requires any other block,
16


2 1 ~5153

the stored data can be updated in block unit. This improves
the efficiency of the expanding operation.
It is also preferable that a memory for storing the image
data in a plurality of expanded blocks in the same
arrangement as in the image frames. The data may be read out
in a given sequence, for example, for each horizontal line,
the necessary data portion being only extracted by a gate
circuit. In such a case, such a memory is preferably of the
same structure as that of a block line memory that will be
described later.
Alternatively, data within the necessary range may only
be read out from a memory in which image data of a plurality
of blocks have been stored, the data read then being supplied
to the decoding section 101. In other words, only the
aforementioned data of pXq pixels may be sequentially read
out and supplied to the decoding section 101.
Fig. 10 is a timing chart in the process. In this
figure, reference numeral 280 designates a block decoding
time required to decode one block at the decoding section
101; 281 a compressing time required to compress one block at
the compre~sing section 102; and 282 an expanding time
required to expand the necessary data (pXQ pixels) required
by the decoding section 101 at the expanding A section 104.
The decoding section 101 decodes the data encoded in
block unit within the block decoding time 280. At this time,
the data of pXQ pixels from the forecast/display frame
memory section 103 at any start position is required as
17


2185753
forecast data. Thus, the expanding A section 104 retrieves
necessary data from the forecast/display frame memory section
103 in response to a request of the decoding section 101, the
data read then being expanded and supplied to the decoding
section 101. The expanding time 282 is the time required to
supply the data to the decoding section 101 starting from the
request of the decoding section 101 to expanding A section
104. The decoded data 151 is transferred from the decoding
section 101 to the compressing section 102. The transferred
data is then completely compressed wlthin a time through
which the decoded data 151 of the next block is transferred
from the decoding section 101 to the compressing section 102.
The compressed data is then written into the forecast/display
frame memory section 103.
In such a manner, the decoding operation for encoded
dynamic images can be accomplished in real time. Even if the
decoded images are compressed and written into the frame
memory to decrease the amount of information, the system can
be operated without problem.
Fig. 11 shows the structure of the expanding B section
105. In this figure, reference numeral 270 represents an
expanding section; and 271 a block line memory.
The expanding B section 105 receives the data of each
block read out from the forecast/display frame memory section
103. The inputted block data is first expanded by the
expanding section 270. The expanded data is then
sequentially stored in the block line memory 271 at a given
18


2 1 85753
-



location for each block. The block line memory 271 has a
capacity sufficient to accumulate all the horizontal blocks
(block line) of the image frame 220. If it is assumed, for
example, that the horizontal length of the image frame 220
includes pixels equal in number to T and has blocks to be
compressed that are equal in number to J, the block line
memory 271 will have a capacity corresponding to the blocks
equal in number to J.
On the other hand, the reading of blocks is carried out
for each pixel along the scan lines forming the image (i.e.,
in the left-to-right direction sp~nn;ng between the blocks),
rather than in such block unit as shown in Fig. 12. In other
words, the data of all the pixels on one horizontal scan line
will be read out sequentially. When the reading operation is
terminated for one horizontal scan line, the data of all the
pixels on the next horizontal scan line will be read out.
Such a procedure will be repeated.
In such an arrangement, the reading operation can be
carried out in the direction of raster by accumulating the
data compressed in block unit by one block line at a time.
These data will be outputted for displaying an image. The
displaying signal can be provided, for example, by reading
out the data on one horizontal scan line in synchronism with
a horizontal synchronizing signal that defines one horizontal
scan line for a displayed scene.
Fig. 13 shows different types of encoded trains; Fig. 14
is a flow chart illustrating the operation of the compressing
19


2 1 85753

section; and Fig. 15 is a schematic bit map of a forecast
frame memory that holds the compressed data.
As shown in Fig. 13, the encoded data trains are of a
bidirectional forecast type and a unidirectional forecast
type. More particularly, the bidirectional forecast type
encoded data train is adapted to decode an image by using the
data in both the forward and backward frames as forecast
data. The unidirectional forecast type encoded data train is
adapted to decode an image by the use of the data in only the
forward frame as forecast data.
As shown in Fig. 14, the type of encoded data train is
judged. If it is a unidirectional forecast type encoded data
train, the decoded data are sequentially written into the
forecast frame memory areas 310a and 310b without being
compressed by the compressing section 102. On the other
hand, if the encoded data train is of the bidirectional
forecast type, the data are compressed into two compressed
frame data which are in turn written into the forecast frame
memory areas 310a and 310b, respectively.
In such a manner, the data will be stored as shown in
Fig. 15. More particularly, the compressed data of the two
frames used for forecast are respectively stored in the
forecast frame areas 310a and 310b of the forecast/display
frame memory section 103 if the encoded data train is of the
bidirectional forecast type. This is used to perform the
decoding operation at the decoding section 101. If the
encoded data train is of the unidirectional forecast type,



- 2 1 8 5 7 ~ 3

the decoding operation is made using the data of one frame
which is stored in the forecast frame memory area 310.
Since the decoding operation can be carried out without
need of the compression if the encoded data train is of the
unidirectional forecast type, the image will not be degraded
due to the compression. If the encoded data train is of the
bidirectional forecast type, two forecast frames can be used
to forecast and encode the other frames between these two
frames. This enables the encoding operation to be made more
efficiently. When the data compressed by the compressing
section 102 are stored in the forecast/display frame memory
section 103, a smaller capacity for that memory can be
maintained.


Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2000-09-12
(22) Filed 1996-09-17
Examination Requested 1996-09-17
(41) Open to Public Inspection 1998-03-18
(45) Issued 2000-09-12
Deemed Expired 2015-09-17

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1996-09-17
Registration of a document - section 124 $0.00 1996-12-12
Maintenance Fee - Application - New Act 2 1998-09-17 $100.00 1998-07-06
Section 8 Correction $200.00 1999-03-23
Maintenance Fee - Application - New Act 3 1999-09-17 $100.00 1999-08-17
Final Fee $300.00 2000-06-06
Maintenance Fee - Application - New Act 4 2000-09-18 $100.00 2000-08-08
Maintenance Fee - Patent - New Act 5 2001-09-17 $150.00 2001-08-17
Maintenance Fee - Patent - New Act 6 2002-09-17 $150.00 2002-08-16
Maintenance Fee - Patent - New Act 7 2003-09-17 $150.00 2003-08-21
Maintenance Fee - Patent - New Act 8 2004-09-17 $200.00 2004-08-19
Maintenance Fee - Patent - New Act 9 2005-09-19 $200.00 2005-08-05
Maintenance Fee - Patent - New Act 10 2006-09-18 $250.00 2006-08-08
Maintenance Fee - Patent - New Act 11 2007-09-17 $250.00 2007-08-08
Maintenance Fee - Patent - New Act 12 2008-09-17 $250.00 2008-08-11
Maintenance Fee - Patent - New Act 13 2009-09-17 $250.00 2009-08-13
Maintenance Fee - Patent - New Act 14 2010-09-17 $250.00 2010-08-23
Maintenance Fee - Patent - New Act 15 2011-09-19 $450.00 2011-09-06
Maintenance Fee - Patent - New Act 16 2012-09-17 $450.00 2012-08-08
Maintenance Fee - Patent - New Act 17 2013-09-17 $450.00 2013-08-14
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
MITSUBISHI DENKI KABUSHIKI KAISHA
Past Owners on Record
ASAI, KOHTARO
MURAKAMI, TOKUMICHI
OHIRA, HIDEO
SHIMADA, TOSHIAKI
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Representative Drawing 1998-03-25 1 5
Cover Page 1997-01-09 1 15
Cover Page 1998-03-25 2 65
Abstract 1997-01-09 1 26
Description 1997-01-09 21 765
Claims 1997-01-09 4 135
Drawings 1997-01-09 15 228
Claims 2000-03-22 4 149
Cover Page 1999-09-29 2 65
Cover Page 2000-09-01 2 66
Representative Drawing 2000-09-01 1 5
Fees 1999-08-17 1 29
Prosecution-Amendment 1999-09-17 2 46
Correspondence 2000-06-06 1 29
Fees 1998-07-06 1 37
Fees 2000-08-08 1 28
Assignment 1996-09-17 8 299
Prosecution-Amendment 1999-07-28 4 167
Correspondence 1999-01-29 2 77
Prosecution-Amendment 1999-03-23 1 50