CA1324435C - Highly efficient coding apparatus - Google Patents
Highly efficient coding apparatusInfo
- Publication number
- CA1324435C CA1324435C CA000612054A CA612054A CA1324435C CA 1324435 C CA1324435 C CA 1324435C CA 000612054 A CA000612054 A CA 000612054A CA 612054 A CA612054 A CA 612054A CA 1324435 C CA1324435 C CA 1324435C
- Authority
- CA
- Canada
- Prior art keywords
- picture element
- value
- video data
- values
- decoded
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
- H04N19/98—Adaptive-dynamic-range coding [ADRC]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
- H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
Abstract
ABSTRACT OF THE DISCLOSURE
A difference between an original digital value of a picture element to be encoded and an original digital value of a spatially adjacent picture element of the picture element is detected by a detecting circuit. The video data of the spatially adjacent picture element is decoded to generate a decoded value by a local decoder. A compressed encoded video data of the picture element wherein a difference between a decoded value of the compressed encoded value data and the decoded value is closest to the difference is generated.
A difference between an original digital value of a picture element to be encoded and an original digital value of a spatially adjacent picture element of the picture element is detected by a detecting circuit. The video data of the spatially adjacent picture element is decoded to generate a decoded value by a local decoder. A compressed encoded video data of the picture element wherein a difference between a decoded value of the compressed encoded value data and the decoded value is closest to the difference is generated.
Description
1324~35 BACKGRO~ND OF THE I~'E~TION
Field of the Invention This invention relates to a highly efficient coding apparatus of image data which is applied to compress and encode the image data.
8RIEF DESCRIP~ION O~ DRAh'I~GS ..
~iq~ 1 is a schematic diagram for use in -`
explanation of a principle o~ a digiti2ation in ADRC;
Figs. 2 and 3 are schematic diagrams for use `
in explanation of a characteristic of a conventional digiti2ing circ~it; `
Fig~ ~ is a block diagram showing a first -~
embodiment o~ the present invention;
Fiqs. 5 and 6 are schematic diagrams for use in explanation of a first embodiment of the present ` ~
inv-ntion; ~ `
~ ig~ 7 is a block dia~ram showing a second embodiment of the present in~ention:
.
~iq. 8 is a bloc~ diagram showing à third ~mbodime~t of the present in~ention: ~nd ;~
Fig. 9 is a block diagram showing the . . .
- details of a distortion deteetion circuit in the third embodiment of the prcsent invention shown in Fig. 8.
' - 1 - ~ . ' A
132~35 DescriPtion of t~e Prior Art various kinds of encoding systems for reducing the number of bits of each pixel or picture element (sample) of the digitized ima~e data by using the correlation of image signals have been proposed. .
As disclosed in the specification of Japanese Patent - ~-Laid Open Publication (JP,A~ No. 144989/1986, the applicant of the present invention has proposed a hi~hly efficient coding apparatus in which a dynamic range as a dif~erence between the maximum value and minimum value of a plurality of pixels included in a two-dimensional block is obtained and the encoding adapted to the dynamic range is executed. On the ~ -other hand, as shown in the specification of Japanese Patent Laid Open Publication (JP,A) No. 92626/1987, ~
thcre has been proposed a highly efficient coding ..
apparatus in which the encoding adapted to the :`.
dynamic r~nge is executed with respect to a three-dimensional block which is formed by pixels in a plurality of areas each belonging to a plurality of frames. Further, ~s disclosed in the specification - lA -"'`'"''.'',''`' A
-: ~32~43~
of Japanese Patent Laid Open Publication (JP,A) No.
128621/1985, there has been proposed a variable length encoding method in which the number of bits -changes in accordance with the dynamic range so that maximum distortion which occurs upon digitizati~n becomes constant. - :-The above encoding methods adapted to the dynamic range (hereinafter, abbreviated to ADRCs) relate ~o the highly efficient coding methods whereby `;
the number of ~its per pixel is reduced by using the `.
fact that images have a strong correlation in a small : .
area ~block) which is obtained by dividing one picture plane. That is, the di~ference between the .`
minimum or ma~imum value in tha block and the level of , .
each pixel becomes smaller than the original level and the difference can be digitized by the number of bits which is smaller than the number of original bits~ -The present invention can be applied to the digitization of the level which was standardized by the minimum or maximum value in the foregoing ADRC.
However, this in~ention is not limited to the ADRC ..
but can be also applied to a digitizing circuit for e~pressing a digital .image signal by a predetermined - :
number of bits in a manner similar to the ADRC.
As shown in Fig. 1, in the ADRC for : .
'., ~
Field of the Invention This invention relates to a highly efficient coding apparatus of image data which is applied to compress and encode the image data.
8RIEF DESCRIP~ION O~ DRAh'I~GS ..
~iq~ 1 is a schematic diagram for use in -`
explanation of a principle o~ a digiti2ation in ADRC;
Figs. 2 and 3 are schematic diagrams for use `
in explanation of a characteristic of a conventional digiti2ing circ~it; `
Fig~ ~ is a block diagram showing a first -~
embodiment o~ the present invention;
Fiqs. 5 and 6 are schematic diagrams for use in explanation of a first embodiment of the present ` ~
inv-ntion; ~ `
~ ig~ 7 is a block dia~ram showing a second embodiment of the present in~ention:
.
~iq. 8 is a bloc~ diagram showing à third ~mbodime~t of the present in~ention: ~nd ;~
Fig. 9 is a block diagram showing the . . .
- details of a distortion deteetion circuit in the third embodiment of the prcsent invention shown in Fig. 8.
' - 1 - ~ . ' A
132~35 DescriPtion of t~e Prior Art various kinds of encoding systems for reducing the number of bits of each pixel or picture element (sample) of the digitized ima~e data by using the correlation of image signals have been proposed. .
As disclosed in the specification of Japanese Patent - ~-Laid Open Publication (JP,A~ No. 144989/1986, the applicant of the present invention has proposed a hi~hly efficient coding apparatus in which a dynamic range as a dif~erence between the maximum value and minimum value of a plurality of pixels included in a two-dimensional block is obtained and the encoding adapted to the dynamic range is executed. On the ~ -other hand, as shown in the specification of Japanese Patent Laid Open Publication (JP,A) No. 92626/1987, ~
thcre has been proposed a highly efficient coding ..
apparatus in which the encoding adapted to the :`.
dynamic r~nge is executed with respect to a three-dimensional block which is formed by pixels in a plurality of areas each belonging to a plurality of frames. Further, ~s disclosed in the specification - lA -"'`'"''.'',''`' A
-: ~32~43~
of Japanese Patent Laid Open Publication (JP,A) No.
128621/1985, there has been proposed a variable length encoding method in which the number of bits -changes in accordance with the dynamic range so that maximum distortion which occurs upon digitizati~n becomes constant. - :-The above encoding methods adapted to the dynamic range (hereinafter, abbreviated to ADRCs) relate ~o the highly efficient coding methods whereby `;
the number of ~its per pixel is reduced by using the `.
fact that images have a strong correlation in a small : .
area ~block) which is obtained by dividing one picture plane. That is, the di~ference between the .`
minimum or ma~imum value in tha block and the level of , .
each pixel becomes smaller than the original level and the difference can be digitized by the number of bits which is smaller than the number of original bits~ -The present invention can be applied to the digitization of the level which was standardized by the minimum or maximum value in the foregoing ADRC.
However, this in~ention is not limited to the ADRC ..
but can be also applied to a digitizing circuit for e~pressing a digital .image signal by a predetermined - :
number of bits in a manner similar to the ADRC.
As shown in Fig. 1, in the ADRC for : .
'., ~
- 2 - , ,':..' 132~3~
performing the digitization of two bits, a dynamic range DR in a block as a difference between the maximum value MAX and minimum value MIN is uniformly divided into four level ranges and the value of the pixel from which the minimum value NIN was eliminated is expressed by the digiti2ation code of two bits respectively corresponding to the level ranges. On the decoding side, one of central decoding representative levels I0 to I3 in each level range is decoded from the dynamic range DR and the digitization code, and the minimum value MIN is added to the decoded value, so that the pixel data in the block is reconstructed. ;:"`
Fig. 2 shows an example of the digitization ;
in the aDRc. Fig. 2 shows an example of a one-dimensional ADRC in which one block is constructed by six pixels which are continuous in the horizontal direction. Data indicated by O denotes true values of the pixels in the block. Therefore, the digitization has a horizontal change indicated by a . .
solid line ~1. In the case where the encoding was executed by the ADRC of two bits, reconstruction `
levels indicated~by x are obtained on the decoding `"
side and a change in signal shown by a broken line 42 :
occurs in the reconstructed image.
In the conventional digitization, the level ~ ''. .' ~:
: . .
,. .
performing the digitization of two bits, a dynamic range DR in a block as a difference between the maximum value MAX and minimum value MIN is uniformly divided into four level ranges and the value of the pixel from which the minimum value NIN was eliminated is expressed by the digiti2ation code of two bits respectively corresponding to the level ranges. On the decoding side, one of central decoding representative levels I0 to I3 in each level range is decoded from the dynamic range DR and the digitization code, and the minimum value MIN is added to the decoded value, so that the pixel data in the block is reconstructed. ;:"`
Fig. 2 shows an example of the digitization ;
in the aDRc. Fig. 2 shows an example of a one-dimensional ADRC in which one block is constructed by six pixels which are continuous in the horizontal direction. Data indicated by O denotes true values of the pixels in the block. Therefore, the digitization has a horizontal change indicated by a . .
solid line ~1. In the case where the encoding was executed by the ADRC of two bits, reconstruction `
levels indicated~by x are obtained on the decoding `"
side and a change in signal shown by a broken line 42 :
occurs in the reconstructed image.
In the conventional digitization, the level ~ ''. .' ~:
: . .
,. .
-.
. - ~ " ~
of the original pixel is substituted to the nearest decoding repre~entative level in order to minimize the digitization error and to improve the S/N ratio.
However, there is a case where a visually conspicuous deterioration occurs in the reconstructed image even -if the image is quantitatively good. In the example shown in Fig. 2, the original smooth horizontal change 41 results in the rough change 42 af~er the reconstruction. The visually conspicuous noises are -genereted in the reconstructed image. These noises are such that the snow noises occuring in the television received image at the weak electric field are made fine and are the jitter-like noises, The occurence of such a problem is based on the fact that when human beings recognize an image, they are sensitive to the differentiating characteristic of the image.
~ ig. 3 shows another example of the digitization in the ADRC. Fig. 3 shows a time change of pixels at the positions which rèspectively belong `~`
to six frames which are continuous in the time direction and spatially correspond to those frames.
For simplicity, it is assumed that each block in which the six pixels are included has the equal ~ `
maYimum value NAX and the equal minimum value MIN. ``-The data shown by O denotes the true values of the - .
. - ~ " ~
of the original pixel is substituted to the nearest decoding repre~entative level in order to minimize the digitization error and to improve the S/N ratio.
However, there is a case where a visually conspicuous deterioration occurs in the reconstructed image even -if the image is quantitatively good. In the example shown in Fig. 2, the original smooth horizontal change 41 results in the rough change 42 af~er the reconstruction. The visually conspicuous noises are -genereted in the reconstructed image. These noises are such that the snow noises occuring in the television received image at the weak electric field are made fine and are the jitter-like noises, The occurence of such a problem is based on the fact that when human beings recognize an image, they are sensitive to the differentiating characteristic of the image.
~ ig. 3 shows another example of the digitization in the ADRC. Fig. 3 shows a time change of pixels at the positions which rèspectively belong `~`
to six frames which are continuous in the time direction and spatially correspond to those frames.
For simplicity, it is assumed that each block in which the six pixels are included has the equal ~ `
maYimum value NAX and the equal minimum value MIN. ``-The data shown by O denotes the true values of the - .
, 132~i~i3~i pixels. Therefore, there is a change in the time direction shown by a solid line 141. In the case where the encoding was executed by the ADR~ of two bits, the reconstruction levels shown by x are ~ -obtained on the decoding side and a change in signal shown by a broken line 142 occurs in the reconstructed image. `
In the example shown in Fig. 3, the original smooth change 141 in the time direction results in the rough change 142 after the reconstruction. The visually conspicuous noises are generated in the reconstructed image like an example shown in Fig. 2.
OBJI~CTS AND SllM~RY OF THE INVENTION
It is, therefore, an object of the present invention to provide a highly efficient coding apparatus which can preserve spatial change in the ` `
original image signal even if quantitative errors ` `
increase and visually improve the picture quality of the reconstructed image.
It is another object of the invention to provide a higly efficient coding apparatus which can ;~
preserve time dependent change in the original image ~; ..
signal and visually improve the picture quality of ~
the reconstructed image. ;
It is still another object of the invention ~to provide a highly efficient coding apparatus which '; ~' '. ,~ `
. :~
In the example shown in Fig. 3, the original smooth change 141 in the time direction results in the rough change 142 after the reconstruction. The visually conspicuous noises are generated in the reconstructed image like an example shown in Fig. 2.
OBJI~CTS AND SllM~RY OF THE INVENTION
It is, therefore, an object of the present invention to provide a highly efficient coding apparatus which can preserve spatial change in the ` `
original image signal even if quantitative errors ` `
increase and visually improve the picture quality of the reconstructed image.
It is another object of the invention to provide a higly efficient coding apparatus which can ;~
preserve time dependent change in the original image ~; ..
signal and visually improve the picture quality of ~
the reconstructed image. ;
It is still another object of the invention ~to provide a highly efficient coding apparatus which '; ~' '. ,~ `
. :~
- 5 ~
:''.-.. ,','- -:
132443~ ~
is preferably adapted to the characteristics such as pattern, movement amount, and the like of an image and in which the picture quality of the reconstructed image can be visually improved.
According to an aspect of the present --invention, there is provided a highly efficient coding apparatus for coding original digital video data having n bits for each picture element to provide compressed video data having the number of bits less than n for each picture element, comprising:
first detecting means for detecting a first difference between an original digital value of a first picture element to be encoded and an original dlgital value of a spatially adjacent picture element of the first picture èlement, i`
- first local decoding means for decoding encoded video data of the spatially adjacent picture element to generate a first decoded value, and .
generating means for generating compressed ` -encoded video data of the first picture element `.
wherein a difference between a decoded value of the :.
compressed encoded video data and the first decoded ~ ~- value is closest to ~he first difference.
- - According to another aspect of the ~-invention, there is provided a highly efficient !.
coding apparatus for coding original digital video - 6 - ~ ' 132~435 data having n bits for each picture element to provide .
compressed video data having the number of bits less than n for each picture element, comprising:
first detecting means for detecting a first difference between an original digital value of a first picture element to be encoded and an original digital value of a timely adjacent and spatially identical picture element of the first picture -element, first local decoding means for decoding .
encoded video data of the timely adjacent and `
spatially identical pic~ure element to generate a `
first decoded vaiue, and generating means for generating compressed `.:
encoded video data of first picture element wherein a difference between a decoded value of the compressed .. `
encoded video data and the first decoded value is ~:
closest to the ~irst dif~erence~
.; . ;
According to still another aspect of the in~ention, there is provided a highly efficient .
coding apparatus for coding original digital video - -~
data having n bits for each picture element to provide ` :~
compressed video data having the number of bits less ; . than n for each picture element, comprising: .`.
first local decoding means for decoding all `
` compressed code data and for generating decoded values ....
. . . -~ ; ~ 7 ~ .~
- ,:
: ~, ' ,''"-,.'~.
132~3~
or a first pi~ture element to be encoded, first detecting means for detecting first differences between an original digital value of the first picture element and the each of the decoded values, second detectiny means for detecting second differences between a difference value of the original digital value of the first picture element and an original digital value of spatially adjacent picture element of the first element and difference values of~.
the decoded values and a decoded value of an encoded data of the spatially adjacent picture element, third detecting means for detecting ~hird :
differences between a difference value of the original digital value of the first picture element and an .
original digital value of timely adjacent and spatially identical picture element of the first e~'ement and difference values of the decoded values and a decoded value of an encoded data of the timely adjacent and spatially adjacent picture element, weighting and adding means for multiplying first, second and third weighting coefficients to the first, second and third differences, respectively and `
for adding corresponding ones of the multiplied first, second and thlrd differences together to . .
generate added values, . ~ ;
1 ,,..`` .;
132~43~
minimum detecting means supplied ~ith the added values and for detecting a minimum value thereof, and code selecting means for se~ecting one of compressed code data corresPonding to the minimum value, ~he above, and other, o~jects, features and `
advantages of the present invention will become readily apparent from the following de~ailed description thereof which is to be read in connection ~ .
~ith the accompanying dra~inss.
. .
~ ;~
`"`. ': '.
. ~ .
.~ ' ' ' '' .
..
:~ . '' ',-' ~ .'' ~': `' "
~ ~ 9 - "''`'"'''' A : ~
132443~
DES~RIP~ION OF THE PREFERRED EM~ODIXE~
A first embodiment of the present invention will ~e described hereinbelow with reference to the drawings.
In ~ig. 4, a digital video signal in which, for instance, one pixel (one sample) is digitized to eight bits is supplied to an input terminal shown by reference numeral 1~ The order of the data of the input digital video signal is chanqed from the scanning order to the order of blocks by a block segmentation circuit 2. ~or instance, a picture `
plane of one frame is divided into small areas and (~ x ~ = 16 pixels) blocks are formed as shown in ~ig.
~. In ~ig. 5, N-1 deno~es a preceding block and ~
indicates an objective block to be encoded. In the block, the data of the top pixel at the left edge when i it is seen toward the diagram is first transmitted. ``
~he data of three pixels arranged in the horizontal direction are then transmitted. ~urther, on the second line, data arc similarly transmitted.
~inally, data of the lowest pixel at the right edge is transmitted~
An ou~put si~nal o~ the bloc' se;men~a~iol; `` -; circuit 2 is supplied to a maximum value and minimum :
:` :'' ~
~ ~ ` . ' ' :
. ' value detecting circuit 3. The maximum value MAX and the minimum value MIN of the pixels included in each block are detected, respectively. The maximum value NAX and the minimum value MIN are supplied to a subtracting circuit 4 and a dynamic range DR as a difference between them is calculated. The dynamic range DR and the minimum value MIN are supplied to a frame segmentation circuit 5. In the frame segmentation circuit 5, th~ dynamic range DR, the minimum value NIN, and a digitization code DT, which will be explained hereinlater, are converted into a ~ :
signal format of a frame construction and are subjected to an error correction encoding process as :
necessary. ~ransmission data is obtained to an output terminal 6 of the frame segmentation circuit 5. `
The output signal of the block segmentation `
circuit 2 is supplied to one of the input terminals of ``
a selector 10 through delay circuits 7, 8 and 9. The output signal of the delay circuit 8 is supplied to ;`
the other input terminals of the selector 10. The ~ :
output signal of the delay circuit 7 and the output signal of the selector 10 are supplied to a ~
subtracting circuit 11, and the difference A r in the ~ `
horizontal diraction of the original pixel data (true value) is calculated. Assuming that the true value ;`
of the objective pixel is set to xl and the true ;;
., :` ' ` ' .
- 1 1 - `.'`:
1~244~i value of the pixel which is preceding by one sampling period is set to xo~ (~ r = xl - xo ) ~
A delay amount DL1 of the delay circuit 7 corresponds to the time necessary to detect the maximum value and the minimum value. A delay amount DL2 of the delay circuit 8 corxesponds to the interval in the horizontal direction between pixels, that is, one sampling period. Therefore, the difference ~ r in the horizontal direction between .
the data of the pixel which is precedinq by one sample and the data of the objective pixel to be encoded is : .
generated from the subtracting circuit 11.
In the case of the pixels of the left edge .
column in the block, since the data of the preceding pixel does not eYist in the block, it is necessary to form the difference by using the data of pixel at the ~:.
right edge in the preceding block N-l. When the piYels at the left edge in the block is supplied to the subtracting circuit 11, the selector 10 selects the data of the pixel at the right edge in the preceding block from the delay circuit 9. A delay ~ `
amount DL3 of the delay circuit 9 is set to tone block period - three sampling periods). ~he selector 10 is controlled by a selection signal from a selection signal generating circuit 12. Clock signals ~(a sampling clock and a block clock) from a terminal ~ :", . `
. .
` - 132443~
,, 1~ are supplied to the selection signal generating circuit 12 and the selection signal to control the selector 10 as mentioned above is formed.
The difference ~ r between the true values of the image data from the subtracting circuit 11 is supplied to subtracting circuits 14, 15, 16 and 17. :
The output signals ~ O, ~ 2 and ~ 3 o~ the --subtracting circuits 14- 17 are supplied to a minimum value detecting circuit 18 and the minimum output -signal is detected. The detection signal of the ` :
minimum value detecting circuit 18 is supplied to a code selecting circuit l9 and the digitization code DT `
of two bits is generated from the code selection circuit l9. The digiti8ation code DT is transmi~ted ^
through the frame segmentation circuit S. In the code selecting circuit l9, one of the two-bit .
di~itisation codes (00), (01), (10) and (11) ~ `
corresponding to the decoding representative levels ~:`
IO, Il, 12 and I3 respectively ls selected.
The selecting operation of the code selecting circuit l9 is as follows. ; `
When P O is minimum, (00) is selected as `
the~digitisation code DT.
When P 1 is minimum, (oi) is selected as the digitization code DT.
; When P 2 is minimum, (10) is selected as : ~: ... .
- l 3 --,: .
.
132~435 the digitization code DT.
When ~ 3 is minimum, (11 ) is selected as the digitization code DT .
Signals ~ 0, ~ 2 and ~ 3 are supplied from subtracting circuits 20, 21, 22 and 23 to the subtracting circuits 14~ 1~. The signals ~ 0~ ~ 3 corresponding to the differences between the decoding level (xO) of the pixel preceding the objective pixel and the four decoding representative levels and indicate the predictive change amount respectively. .
The subtracting circuits 14~ 17 and the minimum value detecting circuit 18 detect among the signals ~ 0~ ~ 3, the one closest to the di~ference ~ r in the horizontal direction of the true value of the image . `
data~ In other words, digiti2ation code DT
corresponding to the decoding representative level which generates the change closest to the signal ~.`
change in the horisontal direction of the original image signal is selected with respect to the objective pixel.
Decoding representative levels (MIN ~ I0), (MIN ~ Il), (MIN ~ I2) and (MIN ~ I3) formed by local decoders 28, 29, 30 and 31 are supplied to the `
subtracting circuits 20~ 23. In order to generate `.` .
these decoding representative levels, the dynamic .::
range DR and the minimum value MIN are supplied to the ~ .
.
". ': ' : ~ - 1 4 - ::~
''';.,''`,:
132~3~
local decoders 28~ 31. Also, two-bit digitization codes (00), (01), (10) and (11) are supplied from terminals 24, 25, 26 and 2?, respectively. The local decoders 28~ 31 and 32 comprise RONs to which the dynamic range DR and digitization code DT are supplied as addresses. The minimum value MIN is added to the data read out of the ROMs.
The decodinq level xO of the pixel preceding the objective pixel is formed by the local decoder 32, delay circuits 33, 34 and 35, and a selector 35.
A digitization code DT from the code selecting circuit 19 is supplied to the local decoder 32. A decoding level of the objective pixel is generated from the -:`
local decoder 32. The decoding level is supplied to ~`
one input terminal of the selector 35 through the delay circuit 33 having the delay amount DL2 of one sampling period. An output signal of the delay circuit 33 is supplied to the other input terminal of -the selector 35 through the delay circuit 34 having -the delay amount D~3 of lone block period - three sa~pling periods). The selector 35 is controlled by the selection signal from the selection signal generàting circuit 12 in a manner similar to the foregoing selector 10~ ~
The delay circuits 33 and 34 and selector 35 ~ ~ ;
generate the decoding level XO of the preceding pixel , .... ..
: - 1 5 - ;
" ',' ' ' 132~43~
xO of the objective pixel xl in a manner similar to the foregoing delay circuits 8 and 9 and selector 10.
The decoding level is supplied to the subtracting circuits 20~ 23. ~hereforer the signals ~ 0 to ~ 3 which are respectively generated from the subtracting circ~its 20- 23 correspond to the predictive differences between the four decoding representative levels and the decoding level X0 of the preceding ~ `
pixel as will be shown below.
0 = (I0 ~ MIN) - X0 1 = (Il ~ MIN) - xO
2 = (I2 ~ MIN) - X0 ~ 3 = (I3 ~ NIN) - X0 In the subtracting circuits l~~ 17, the `
following output signals are formed~
'' ```' ' P 0 = ~ r - ~ 0 P 1 = ~ r ~
P 2 = ~ r - ~ 2 P 3 = ~ r - ~ 3 Since the minimum one of ~ 0- ~ 3 is . ~
detected by the minimum value detecting circuit 18, :-the digitization code of which the predictive change ;~
~ '` `'., ' ~ . .
- 1 6 - `:~
, .. :.: .
` `" ', '.
amount is closest to the true value of the change amount ~ r is selected by the code selecting circuit 19.
.. ....
It is also effective to execute the digitization such as to accurately express two-dimentional changes in the horisontal direction, vertical direction, oblique direction, and the like without limiting to the differences in the horizontal direction in the above embodiment. For instance, as :
shown in ~ig. 6, in the case where the level of the objective pixel is x and the levels of the peripheral :
pixels at the upper position, left position and the upper oblique position are respectively a, b, and c, the change amount A r of the true value of the . .
objective pixel and the predictive change amounts ~ i `
(i = 0, l, 2, 3) are obtained as the differences between the average values of the levels of the ` ~ .
: :.
peripheral pixels and the level of the objective pisel. That is, .
, ,, r = 13x - a - b - c) ...
A i = ~3Ii - A - B - C) where, A, B, and C denote levels which are obtained by decoding the digitization codes derived with respect :
~ .... .
to a, b, and c, respectively. The digitization code .'''''~
:; ' .
- 1 7 ~
'~''`'," ,'.
132443~
signal generating ~ i which is closest to ~ r is selected.
To obtain the change amount in the space, the predictive value obtained by the spatial prediction can be also used without limiting to the average value. That is, assuming that a predictive value is x', x' = b ~ 1/2 Ic - a) r = x - x' = x - b - 1/2(c - a) i = Ii - s - 1/2 (C - A) . ~ .
' In a manner similar to the above, the digitisation code signal generating ~ i which is ` .
closest to ~ r is selected. . :
Furthermore, the present invention can be ` `
applied to a digitizing circuit in other highly -`~
efficient coding such as ADRC of a variable length, - .
~ ADRC o~ a three-dimenional block, etc. ~ ``
.
: When the first embodiment is applied to an ~ image signal having a change shown by a solid line 41 ;; as in ~iq. 2, the data of the respective pixels are digitised to have the decoding representative value shown by O , and~therefore the change of the : :
reconstructed image results in a smooth change similarly to the original signal as shown by a broken .
. .
~ 1 8 ~
:
~, : ` ' `
132443~
line 43. In this manner, according to the first embodiment, the spatial change of the original image signal can be preserved, so that the generation of the visually conspicuous noises in the reconstructed image can be prevented.
Now, a second embodiment of the present invention will be described with reference to the drawinqs~
In Fig. 7, a digital video signal in which, -for instance, one pixel (one sample) is digitized to `
eight bits is supplied to an input terminal shown by reference numeral 101. The order of the data of the "
input digital video signal is changed from the ; `-scanninq order to the order of blocks by a block ~ `
segmentation circuit 2~ Since a maximum value and ` `
minimum value detecting circuit 103, subtracting ~"`
.
circuit 10~ and frame segmentation circuit 105 having ``~
output terminal 106 have the same construction as the ` `
circuits 3, 4 and 5 in Fig. 4, the detailed `"
description of those is omitted for simplicity.
$he output signal of the block segmentation circuit 102 is supplied to one of the input terminals of a subtracting circuit 109 through delay circuits 107 and 108. A delay amount DL1 of the delay circuit 107 corresponds to the time neccessary to detect the maximum and minimum values. The output signal of the .
' -- 1 9 -- ~
`
delay circuit 107 is supplied to the other input terminal of the subtracting circuit 109. A difference t in the time direction of the original pixel data (true value) is calculated. Assuming that a true value of the objective pixel is set to xl and a true value of a reference pixel which is preceding by one frame period is set to xlO, (~ t = xl - xlO). `
~ he difference ~ t between the true values of the imaqe data from the subtracting circuit 109 is supplied to subtracting circuits 110, 111, 112, and 113. The output signals r 0, ~ 1, r 2 and r 3 of the subtracting circuits 110~ 113 are supplied to a minimum value detecting circuit 114 and the minimum -output signal is detected. The detection signal of ~`
the minimum value detecting circuit 114 is supplied to a code selecting circuit 115 and the digitization code DT of two bi~s is generated from the code solecting circuit 115. The digitization code DT is transmitted through the f~ame segmentation circuit `
105. In the code selecting circuit 115, one of the .
~wo-bit digitisation codes (00), (01~, ~10) and (11) j:`"`
corresponding to the decoding representative levels `
; I0, I1, 12 and I3 is~selected.
The selecting operation of the code "
selecting circuit 115 is as follows.
When r 0 is minimum, (00) is selected as : -: .
- 2 0 - ~ ~
',. :...'' ., ~ . .
132443~
the digitization code DT.
When r 1 is minimum, (01) is selected as the digitization code D~.
When r 2 is minimum, (10) is selected as the digitization code DT.
When r 3 is minimum, (11) is selected as the digitization code DT.
Signals ~ 00, ~ 01, ~ 02 and ^ 03 are -s~pplied from subtractiny circuits 116, 117, 118 and 119 to the subtracting circuits 110~ 113. The signals ~ 00- ~ 03 corresponding to the differences -between the decoding level (X10) of the reference pixel and the four decoding representative levels and indicate the predictive change amount respectively. -The subtracting circuits 110~ 113 and the minimum : .
value detecting circuit 114 detect among the signals 00_ A 03, the one closest to the difference ~ t in the time direction of the true value of the image data. In other words, a digitization code DT
corresponding to the decoding representative level which generates the change closest to the signal change in one frame period of the original image signal is selected with respect to the objective pi~el.
To the subtracting circuits 116- 119, decoding representative levels (MIN + I0), (MIN + Il), ' , - 2 1 - .
~,: ' ' (NIN t I2) and (MIN ~ I3) formed by the local decoders 124, 125, 126 and 127 are supplied. In order to generate the~e decoding representative levels the dynamic range DR and the minimum value MIN are supplied to the local decoders 124~ 127. Also, two-bit digitization codes lOO), (01), (10) and (11) are supplied from terminals 120, 121, 122 and 123, respectively~ The local decoders 124~ 127 and 128 comprise RONs to which the dynamic range DR and digitization code DT are supplied as addresses. The minimum value MIN is added to the data read out of the ~ONs.
The decoding level X10 of the reference pixel is formed by a local decoder 128 and a delay circuits 129 having the delay amount DL2 of one frame ~`
period. A digitization data DT from the code selecting circuit 115 is supplied to a local decoder 128. A decoding level of the objective pixel is generated from the local decoder 128. By passing the decoding level through a delay circuit 129, the decoding le~el xlO of the reference pixel is obtained. ` `
The decoding level is supplied to the subtracting circuits 116- 119. Therefore, the signals ~ 00 to ~ 0~ which are respectively generated from the subtracting circuits 116~ 119 correspond to the predictive difference between the four decodinq :;
- 2 2 - i ,,', :.
......
.: .
1324435 :;
representative levels and the decoding level X10 of . .
the preceding pixel as will be shown below, 00 = (I0 ~ MIN) - X10 '' 01 = ( Il ~ MIN ) - Xl 0 . ` -~ 02 = (I2 ~ MIN~ - X10 a 03 = (I3 ~ MIN) - X10 In the subtracting circuits 110~ 113, the ~.-following output signals are formed. :
T O = ~ t - ~ 00 r 1 = ~ t - ~ 01 r 2 = ~ t _ A 02 T 3 = ~ t - ~ 03 .
Since the minimu~ one o r 0- T 3 iS
detected by the minimum~alue detecting circuit 114, the digitization code of which the predictive change = is closest to tha true value of the change . ~: amount ~ t of the true value is selected by the code ~ .
selecting circuit 115. ` ~ `
Accordlng to the second embodiment, time `` ~
: ~ .
~ dependent change of the original image signai can be ., .
preserved so that the generation of the visually ~ : ; conspicuous noises in the rèconstructed image can be ~ : .. .
~ 2 3 - : ~:
. .
:: ` . ~'`':"' 1324~3~
prevented.
However, according to the first embodiment in which the spatial signal change can be preserved, the generation of the noises in the time direction cannot be prevented~ On the other hand, according to the second embodiment in which the time dependent -:
signal change can be preserved, the generation of the spatial noises cannot be prevented. Noreover, the digitiziny system in which such signal changes are `
significant has a problem such that errors are accumulated.
Therefore, in the third embodiment, a highly efficient coding apparatus which can be adapted preferably to the characteristics such as pattern, movement amount of a picture, and the like of an image ``
and which can improve the picture quality of the reconstructed image visually will be described hereinbelow with reference to Fig. 8~ ~:
In Fig. 8, a digital video signal in which, for instance, one pixel (one sample) is digitized to .
eight bits is supplied to an input terminal shown by "
reference numeral 201. The order of the data of the " :
input digital video signal is changed from the ~ ~.
scanning order to the order of blocks by a block ..
segmentation circuit 202. .
Since the circuits 203, 204 and 206 have the . ;
- 2 4 - ` ;. :
''"''~ ~' 24~3~
same construction as the circuit~ ~, 4 and 5 in Fig. 4, the detailed description of those is omitted, The output signal of the block segmentation circuit 202 is supplied to input terminals 211, 221 and 231 of a distortion detecting circuit 208, an inner space change detecting circuit 209, and a time dependent change detecting circuit 210 through a delay circuit 207. A delay amount DLl of the delay circuit 207 corresponds to the time necessary to detect the maximum and minimum values.
The distortion detecting circuit 208 is the first aritbmetic operating circuit for respectively arithmetically operating differences ~ 0, ~ 2 and ~ 3 between a true value xl of the objective pixel and four decoding representative vatues corresponding to the number of bits. The decodinq representative ~-values are formed by local decoders 241, 242, 243 and ` `
2~. Digitisation codes (00), (01), (10) and (11) each consisting of two bits are supplied from tarminals 245, 2~6, 2~7 and 248 to the local decoders 2~1 to 2~, respectively. In addition, the dynamic range DR and the minimum value MIN are supplied to the local decoders 241 to 244. The distortion detecting circuit 208 has input terminals 212, 213, 214 and 215 to which the above decoding representative values are respectively supplied and output terminals 217, 218, :: ~, ` '.'.. "`
- 2 5 - ` -:. .
132~435 219 and 220 to which the output signals ~ 0 to ~ 3 are extracted.
The inner space chanqe detecting circuit 209 is the second arithmetic operating circuit for calculating a spatial first change amount ~ r from the true value of the objective pixel and the true value of a peripheral pixel which spatially locates in the periphery, for calculating spatial second change amounts ~ 0, ~ 1, A 2 and ~ 3 from the decoding value of the digitization code of the peripheral pixel and the decoding representative values, and for calculating dif~erences ~ 0, ~ 2 and ~ 3 between the first change amount ~ r and the second change .
amounts ~ 0 to ~ 3. The inner space change detecting circuit 209 has input terminals 222, 223, 224 and 225 .
to which the above decoding representative values are " :
respectively supplied, an input terminal 226 to which .
th~ decoded value of the digitization code DT is supplied, and output terminals 227, 228, 229 and 230 to which the differences ~ 0 to ~ 3 are extracted. ` ;
The decoded value of the digitization code DT is formed by a local decoder 257. The dynamic range DR, the minimum value MIN, and the digitization . :~
code DT are supplied to the local decoder 257 and the . --.
level correspondinq to the digitization code DT is reconstructed by the decoding of the ADRC. The local . .
- 2 6 - .:
''' `"''"'''' '~' 1324~3~ -decoders 241, 244 and 257 comprise ROMs to which the dynamic range DR and digitization code are supplied as addresses. The minimum value MIN is added to the data read out of the ROMs.
The time dependent change detecting circuit 210 is the third arithmetic operating circuit for calculating a time dependent third change amount ~ t from the true value of the objective pixel and a true value of a reference pixel which is time precedent to the objective pixel and spatially corresponds thereto, for calculating time dependent fourth change amounts ~ 00, ~ 01, ^ 02 and ^ 03 ~rom the decoded value of the dig~itization code of the reference pixel and the `.
decoding representative values, and for calculating :.
differences T 0, T 1, T 2 and T 3 between the third change amount ~ t and the fourth change amounts ~ 00.` :
to ~ 03. The time dependent change detecting circuit 220 has input terminals 232, 233, 234 and 235 to which the above decoding representative values are respectively supplied, an input terminal 236 to which the decoded value of the digitization code is supplied, and output terminals 237, 238, 239 and 24Q to .
which the o~tput sign:als T O to T 3 are extracted.
Respective output signals of the distortion ; : detecting circuit 208, inner space change detecting circuit 209, and time dependent change detecting : ,, - 2 7 :
' .;
1~2~43~
circuit 210 are synthesized by weighting adding circuits 251, 252, 253 and 254. That is, the differential signals with respect to each of the four decoding representative values are weighted and added.
Assuming that wO, wl, w2 and w3 denote weighting -coefficients, the weighting adding circuit 251 generates a synthesized output ~ 0 which is expressed as follows.
`' ` `.
wO~ 0 ~ wl~ 0 + w2r 0 = ~ 0 ', ' In a manner similar to the above, the weighting adding ` `
circuits 252, 253 and 2S~ generate synthesized outputs ~ 2 and ~ 3 which are expressed as ~ollows. `
., wO~ 1 ~ wlP l ~ w2r l = ~ l ~
wO ~r 2 ~ Wl ~? 2 ~ W2 T 2 = &` 2 - ~ ~
wO~ 3 ~ wl~ 3 ~ w2r 3 = ~ 3 ```
Fixed values or variable values may be used ~ ;
as the weighting coe~ficients wO to w2 and they are .-; . . -set in consideration of the characteristics of the . . .
input image or the like. `
The synthesized outputs ~ 1 to ~ 3 from the -" '.`.
''''.` `''"' ``
., , . ~ . .
weighting adding circuits 251 to 254 are supplied to a minimum value detecting circuit 255. The minimum value detecting circuit 255 generates a detecti~n signal indicative of the minimum one of the synthesized outputs ~ 1 to ~ 3 . The detection signal is supplied to a code selecting circuit 256.
The digitization code DT of two bits which is specified by the detection signal is generated from the code selecting circuit 256. The digitization code DT is transmitted through the frame segmentation circuit 205~ That is, in the code selecting circuit 256, one of the two-bit digiti2ation codes (00), (01), "
~lO) and (11) corresponding to the decoding representative levels I0, Il, I2 and I3 is selected.
The selecting operation of the code selecting circuit 256 is as follows~ ``
When ~ O is minimum, (00~ is selected as the digitization code DT.
When ~ 1 is minimum, (01) is selected as the digitisation code DT.
When ~ 2 is minimum, (10) is selected as the digitisation code DT.
When ~ ~ is minimum, ~11) is selected as `
the digitization code DT. .:
Although not shown, on the reception side, :
the reception data is supplied to a frame - 2 9 - :
,..
~324~35 desegmentation circuit and the dynamic range DR, the minimum value MIN, and the digitization code DT are sepatated by the frame desegmentation eircuit. The dynamic range DR and the digitization code DT are supplied to the ROMS. The decoding level after the minimum value was eliminated is formed. The minimum value NIN is added to the decoding level. Further, the reconstruction levels obtained as the results of the addition are changed to the original scanning order by a block separating circuit. ~-As shown in Fig. 9, the distortion detecting `:
circuit 208 comprises subtracting circuits 261, 262, 263 and 26~. The true value xl of the objective pixel is commonly supplied from the input terminal 211 to `
the subtracting circuits 261 to 264, respectively. -O~ the other hand, the decoding representative levels tNIN ~ I0),tMIN ~ Il), (MIN ~ I2) and ~MIN ~ I3) are supplied from the input terminals 212 to 215 to the `` `
subtracting circuits 261 to 264, respectively~ `
Therefore, the following output signals a 0 to a 3 ~. -are obtained at the output terminals 217 to 220 of the subtracting circiuts 261 to 264, respectively.
R 0 = tI0 ~ NIN) - xl -1 = ~I1 ~ MIN) - xl 2 = tl2 ~ MIN) - xl .. ..
' ' :.:", - 3 0 - ;
"' :, a 3 = ( I 3 ~ MIN ) - Xl The output signals ~ 0 to ~ 3 of the above distortion detecting circuit 208 indicate the differences between the true value xl of the objective pixel and the decoding representative levels. The two-bit digitization code corresponding to the minimum one of the ~ 0 to ~ 3 expresses xl by the minimum distortion (the S/N ratio is best).
The inner space change detecting circuit 209 has a construction corresponding to that shown in Fig. ~. Similarly the construction of the time dependent change detecting circuit 210 corresponds to that shown in Fig~ 7. ~here~ore, the detailed description of these circuits 209 and 210 is omitted, ~ ; .
respectively. -~
he third embodiment is adapted to the `
cbaracteristics such as pattern, movement amount, and ; the like of the original image signal and the S/N
r~ r~t~o càn be improved. The`spatial change or time dependent change of tbe original image signal can be preserved, so that the generation of the visually `
conspicuous noises in the reconstructed image can be -prevented. ~ ~~
aving described a specific preferred embodiment of the present invention with reference to ^; ~; :
, , . .
~ "~C
1324~35 the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or the spirit of the invention as defined in the appended claims.
'`^"'`'`~ "",' ' `~,''`'`' `', .
'', - 3 2 - .. .
:''.-.. ,','- -:
132443~ ~
is preferably adapted to the characteristics such as pattern, movement amount, and the like of an image and in which the picture quality of the reconstructed image can be visually improved.
According to an aspect of the present --invention, there is provided a highly efficient coding apparatus for coding original digital video data having n bits for each picture element to provide compressed video data having the number of bits less than n for each picture element, comprising:
first detecting means for detecting a first difference between an original digital value of a first picture element to be encoded and an original dlgital value of a spatially adjacent picture element of the first picture èlement, i`
- first local decoding means for decoding encoded video data of the spatially adjacent picture element to generate a first decoded value, and .
generating means for generating compressed ` -encoded video data of the first picture element `.
wherein a difference between a decoded value of the :.
compressed encoded video data and the first decoded ~ ~- value is closest to ~he first difference.
- - According to another aspect of the ~-invention, there is provided a highly efficient !.
coding apparatus for coding original digital video - 6 - ~ ' 132~435 data having n bits for each picture element to provide .
compressed video data having the number of bits less than n for each picture element, comprising:
first detecting means for detecting a first difference between an original digital value of a first picture element to be encoded and an original digital value of a timely adjacent and spatially identical picture element of the first picture -element, first local decoding means for decoding .
encoded video data of the timely adjacent and `
spatially identical pic~ure element to generate a `
first decoded vaiue, and generating means for generating compressed `.:
encoded video data of first picture element wherein a difference between a decoded value of the compressed .. `
encoded video data and the first decoded value is ~:
closest to the ~irst dif~erence~
.; . ;
According to still another aspect of the in~ention, there is provided a highly efficient .
coding apparatus for coding original digital video - -~
data having n bits for each picture element to provide ` :~
compressed video data having the number of bits less ; . than n for each picture element, comprising: .`.
first local decoding means for decoding all `
` compressed code data and for generating decoded values ....
. . . -~ ; ~ 7 ~ .~
- ,:
: ~, ' ,''"-,.'~.
132~3~
or a first pi~ture element to be encoded, first detecting means for detecting first differences between an original digital value of the first picture element and the each of the decoded values, second detectiny means for detecting second differences between a difference value of the original digital value of the first picture element and an original digital value of spatially adjacent picture element of the first element and difference values of~.
the decoded values and a decoded value of an encoded data of the spatially adjacent picture element, third detecting means for detecting ~hird :
differences between a difference value of the original digital value of the first picture element and an .
original digital value of timely adjacent and spatially identical picture element of the first e~'ement and difference values of the decoded values and a decoded value of an encoded data of the timely adjacent and spatially adjacent picture element, weighting and adding means for multiplying first, second and third weighting coefficients to the first, second and third differences, respectively and `
for adding corresponding ones of the multiplied first, second and thlrd differences together to . .
generate added values, . ~ ;
1 ,,..`` .;
132~43~
minimum detecting means supplied ~ith the added values and for detecting a minimum value thereof, and code selecting means for se~ecting one of compressed code data corresPonding to the minimum value, ~he above, and other, o~jects, features and `
advantages of the present invention will become readily apparent from the following de~ailed description thereof which is to be read in connection ~ .
~ith the accompanying dra~inss.
. .
~ ;~
`"`. ': '.
. ~ .
.~ ' ' ' '' .
..
:~ . '' ',-' ~ .'' ~': `' "
~ ~ 9 - "''`'"'''' A : ~
132443~
DES~RIP~ION OF THE PREFERRED EM~ODIXE~
A first embodiment of the present invention will ~e described hereinbelow with reference to the drawings.
In ~ig. 4, a digital video signal in which, for instance, one pixel (one sample) is digitized to eight bits is supplied to an input terminal shown by reference numeral 1~ The order of the data of the input digital video signal is chanqed from the scanning order to the order of blocks by a block segmentation circuit 2. ~or instance, a picture `
plane of one frame is divided into small areas and (~ x ~ = 16 pixels) blocks are formed as shown in ~ig.
~. In ~ig. 5, N-1 deno~es a preceding block and ~
indicates an objective block to be encoded. In the block, the data of the top pixel at the left edge when i it is seen toward the diagram is first transmitted. ``
~he data of three pixels arranged in the horizontal direction are then transmitted. ~urther, on the second line, data arc similarly transmitted.
~inally, data of the lowest pixel at the right edge is transmitted~
An ou~put si~nal o~ the bloc' se;men~a~iol; `` -; circuit 2 is supplied to a maximum value and minimum :
:` :'' ~
~ ~ ` . ' ' :
. ' value detecting circuit 3. The maximum value MAX and the minimum value MIN of the pixels included in each block are detected, respectively. The maximum value NAX and the minimum value MIN are supplied to a subtracting circuit 4 and a dynamic range DR as a difference between them is calculated. The dynamic range DR and the minimum value MIN are supplied to a frame segmentation circuit 5. In the frame segmentation circuit 5, th~ dynamic range DR, the minimum value NIN, and a digitization code DT, which will be explained hereinlater, are converted into a ~ :
signal format of a frame construction and are subjected to an error correction encoding process as :
necessary. ~ransmission data is obtained to an output terminal 6 of the frame segmentation circuit 5. `
The output signal of the block segmentation `
circuit 2 is supplied to one of the input terminals of ``
a selector 10 through delay circuits 7, 8 and 9. The output signal of the delay circuit 8 is supplied to ;`
the other input terminals of the selector 10. The ~ :
output signal of the delay circuit 7 and the output signal of the selector 10 are supplied to a ~
subtracting circuit 11, and the difference A r in the ~ `
horizontal diraction of the original pixel data (true value) is calculated. Assuming that the true value ;`
of the objective pixel is set to xl and the true ;;
., :` ' ` ' .
- 1 1 - `.'`:
1~244~i value of the pixel which is preceding by one sampling period is set to xo~ (~ r = xl - xo ) ~
A delay amount DL1 of the delay circuit 7 corresponds to the time necessary to detect the maximum value and the minimum value. A delay amount DL2 of the delay circuit 8 corxesponds to the interval in the horizontal direction between pixels, that is, one sampling period. Therefore, the difference ~ r in the horizontal direction between .
the data of the pixel which is precedinq by one sample and the data of the objective pixel to be encoded is : .
generated from the subtracting circuit 11.
In the case of the pixels of the left edge .
column in the block, since the data of the preceding pixel does not eYist in the block, it is necessary to form the difference by using the data of pixel at the ~:.
right edge in the preceding block N-l. When the piYels at the left edge in the block is supplied to the subtracting circuit 11, the selector 10 selects the data of the pixel at the right edge in the preceding block from the delay circuit 9. A delay ~ `
amount DL3 of the delay circuit 9 is set to tone block period - three sampling periods). ~he selector 10 is controlled by a selection signal from a selection signal generating circuit 12. Clock signals ~(a sampling clock and a block clock) from a terminal ~ :", . `
. .
` - 132443~
,, 1~ are supplied to the selection signal generating circuit 12 and the selection signal to control the selector 10 as mentioned above is formed.
The difference ~ r between the true values of the image data from the subtracting circuit 11 is supplied to subtracting circuits 14, 15, 16 and 17. :
The output signals ~ O, ~ 2 and ~ 3 o~ the --subtracting circuits 14- 17 are supplied to a minimum value detecting circuit 18 and the minimum output -signal is detected. The detection signal of the ` :
minimum value detecting circuit 18 is supplied to a code selecting circuit l9 and the digitization code DT `
of two bits is generated from the code selection circuit l9. The digiti8ation code DT is transmi~ted ^
through the frame segmentation circuit S. In the code selecting circuit l9, one of the two-bit .
di~itisation codes (00), (01), (10) and (11) ~ `
corresponding to the decoding representative levels ~:`
IO, Il, 12 and I3 respectively ls selected.
The selecting operation of the code selecting circuit l9 is as follows. ; `
When P O is minimum, (00) is selected as `
the~digitisation code DT.
When P 1 is minimum, (oi) is selected as the digitization code DT.
; When P 2 is minimum, (10) is selected as : ~: ... .
- l 3 --,: .
.
132~435 the digitization code DT.
When ~ 3 is minimum, (11 ) is selected as the digitization code DT .
Signals ~ 0, ~ 2 and ~ 3 are supplied from subtracting circuits 20, 21, 22 and 23 to the subtracting circuits 14~ 1~. The signals ~ 0~ ~ 3 corresponding to the differences between the decoding level (xO) of the pixel preceding the objective pixel and the four decoding representative levels and indicate the predictive change amount respectively. .
The subtracting circuits 14~ 17 and the minimum value detecting circuit 18 detect among the signals ~ 0~ ~ 3, the one closest to the di~ference ~ r in the horizontal direction of the true value of the image . `
data~ In other words, digiti2ation code DT
corresponding to the decoding representative level which generates the change closest to the signal ~.`
change in the horisontal direction of the original image signal is selected with respect to the objective pixel.
Decoding representative levels (MIN ~ I0), (MIN ~ Il), (MIN ~ I2) and (MIN ~ I3) formed by local decoders 28, 29, 30 and 31 are supplied to the `
subtracting circuits 20~ 23. In order to generate `.` .
these decoding representative levels, the dynamic .::
range DR and the minimum value MIN are supplied to the ~ .
.
". ': ' : ~ - 1 4 - ::~
''';.,''`,:
132~3~
local decoders 28~ 31. Also, two-bit digitization codes (00), (01), (10) and (11) are supplied from terminals 24, 25, 26 and 2?, respectively. The local decoders 28~ 31 and 32 comprise RONs to which the dynamic range DR and digitization code DT are supplied as addresses. The minimum value MIN is added to the data read out of the ROMs.
The decodinq level xO of the pixel preceding the objective pixel is formed by the local decoder 32, delay circuits 33, 34 and 35, and a selector 35.
A digitization code DT from the code selecting circuit 19 is supplied to the local decoder 32. A decoding level of the objective pixel is generated from the -:`
local decoder 32. The decoding level is supplied to ~`
one input terminal of the selector 35 through the delay circuit 33 having the delay amount DL2 of one sampling period. An output signal of the delay circuit 33 is supplied to the other input terminal of -the selector 35 through the delay circuit 34 having -the delay amount D~3 of lone block period - three sa~pling periods). The selector 35 is controlled by the selection signal from the selection signal generàting circuit 12 in a manner similar to the foregoing selector 10~ ~
The delay circuits 33 and 34 and selector 35 ~ ~ ;
generate the decoding level XO of the preceding pixel , .... ..
: - 1 5 - ;
" ',' ' ' 132~43~
xO of the objective pixel xl in a manner similar to the foregoing delay circuits 8 and 9 and selector 10.
The decoding level is supplied to the subtracting circuits 20~ 23. ~hereforer the signals ~ 0 to ~ 3 which are respectively generated from the subtracting circ~its 20- 23 correspond to the predictive differences between the four decoding representative levels and the decoding level X0 of the preceding ~ `
pixel as will be shown below.
0 = (I0 ~ MIN) - X0 1 = (Il ~ MIN) - xO
2 = (I2 ~ MIN) - X0 ~ 3 = (I3 ~ NIN) - X0 In the subtracting circuits l~~ 17, the `
following output signals are formed~
'' ```' ' P 0 = ~ r - ~ 0 P 1 = ~ r ~
P 2 = ~ r - ~ 2 P 3 = ~ r - ~ 3 Since the minimum one of ~ 0- ~ 3 is . ~
detected by the minimum value detecting circuit 18, :-the digitization code of which the predictive change ;~
~ '` `'., ' ~ . .
- 1 6 - `:~
, .. :.: .
` `" ', '.
amount is closest to the true value of the change amount ~ r is selected by the code selecting circuit 19.
.. ....
It is also effective to execute the digitization such as to accurately express two-dimentional changes in the horisontal direction, vertical direction, oblique direction, and the like without limiting to the differences in the horizontal direction in the above embodiment. For instance, as :
shown in ~ig. 6, in the case where the level of the objective pixel is x and the levels of the peripheral :
pixels at the upper position, left position and the upper oblique position are respectively a, b, and c, the change amount A r of the true value of the . .
objective pixel and the predictive change amounts ~ i `
(i = 0, l, 2, 3) are obtained as the differences between the average values of the levels of the ` ~ .
: :.
peripheral pixels and the level of the objective pisel. That is, .
, ,, r = 13x - a - b - c) ...
A i = ~3Ii - A - B - C) where, A, B, and C denote levels which are obtained by decoding the digitization codes derived with respect :
~ .... .
to a, b, and c, respectively. The digitization code .'''''~
:; ' .
- 1 7 ~
'~''`'," ,'.
132443~
signal generating ~ i which is closest to ~ r is selected.
To obtain the change amount in the space, the predictive value obtained by the spatial prediction can be also used without limiting to the average value. That is, assuming that a predictive value is x', x' = b ~ 1/2 Ic - a) r = x - x' = x - b - 1/2(c - a) i = Ii - s - 1/2 (C - A) . ~ .
' In a manner similar to the above, the digitisation code signal generating ~ i which is ` .
closest to ~ r is selected. . :
Furthermore, the present invention can be ` `
applied to a digitizing circuit in other highly -`~
efficient coding such as ADRC of a variable length, - .
~ ADRC o~ a three-dimenional block, etc. ~ ``
.
: When the first embodiment is applied to an ~ image signal having a change shown by a solid line 41 ;; as in ~iq. 2, the data of the respective pixels are digitised to have the decoding representative value shown by O , and~therefore the change of the : :
reconstructed image results in a smooth change similarly to the original signal as shown by a broken .
. .
~ 1 8 ~
:
~, : ` ' `
132443~
line 43. In this manner, according to the first embodiment, the spatial change of the original image signal can be preserved, so that the generation of the visually conspicuous noises in the reconstructed image can be prevented.
Now, a second embodiment of the present invention will be described with reference to the drawinqs~
In Fig. 7, a digital video signal in which, -for instance, one pixel (one sample) is digitized to `
eight bits is supplied to an input terminal shown by reference numeral 101. The order of the data of the "
input digital video signal is changed from the ; `-scanninq order to the order of blocks by a block ~ `
segmentation circuit 2~ Since a maximum value and ` `
minimum value detecting circuit 103, subtracting ~"`
.
circuit 10~ and frame segmentation circuit 105 having ``~
output terminal 106 have the same construction as the ` `
circuits 3, 4 and 5 in Fig. 4, the detailed `"
description of those is omitted for simplicity.
$he output signal of the block segmentation circuit 102 is supplied to one of the input terminals of a subtracting circuit 109 through delay circuits 107 and 108. A delay amount DL1 of the delay circuit 107 corresponds to the time neccessary to detect the maximum and minimum values. The output signal of the .
' -- 1 9 -- ~
`
delay circuit 107 is supplied to the other input terminal of the subtracting circuit 109. A difference t in the time direction of the original pixel data (true value) is calculated. Assuming that a true value of the objective pixel is set to xl and a true value of a reference pixel which is preceding by one frame period is set to xlO, (~ t = xl - xlO). `
~ he difference ~ t between the true values of the imaqe data from the subtracting circuit 109 is supplied to subtracting circuits 110, 111, 112, and 113. The output signals r 0, ~ 1, r 2 and r 3 of the subtracting circuits 110~ 113 are supplied to a minimum value detecting circuit 114 and the minimum -output signal is detected. The detection signal of ~`
the minimum value detecting circuit 114 is supplied to a code selecting circuit 115 and the digitization code DT of two bi~s is generated from the code solecting circuit 115. The digitization code DT is transmitted through the f~ame segmentation circuit `
105. In the code selecting circuit 115, one of the .
~wo-bit digitisation codes (00), (01~, ~10) and (11) j:`"`
corresponding to the decoding representative levels `
; I0, I1, 12 and I3 is~selected.
The selecting operation of the code "
selecting circuit 115 is as follows.
When r 0 is minimum, (00) is selected as : -: .
- 2 0 - ~ ~
',. :...'' ., ~ . .
132443~
the digitization code DT.
When r 1 is minimum, (01) is selected as the digitization code D~.
When r 2 is minimum, (10) is selected as the digitization code DT.
When r 3 is minimum, (11) is selected as the digitization code DT.
Signals ~ 00, ~ 01, ~ 02 and ^ 03 are -s~pplied from subtractiny circuits 116, 117, 118 and 119 to the subtracting circuits 110~ 113. The signals ~ 00- ~ 03 corresponding to the differences -between the decoding level (X10) of the reference pixel and the four decoding representative levels and indicate the predictive change amount respectively. -The subtracting circuits 110~ 113 and the minimum : .
value detecting circuit 114 detect among the signals 00_ A 03, the one closest to the difference ~ t in the time direction of the true value of the image data. In other words, a digitization code DT
corresponding to the decoding representative level which generates the change closest to the signal change in one frame period of the original image signal is selected with respect to the objective pi~el.
To the subtracting circuits 116- 119, decoding representative levels (MIN + I0), (MIN + Il), ' , - 2 1 - .
~,: ' ' (NIN t I2) and (MIN ~ I3) formed by the local decoders 124, 125, 126 and 127 are supplied. In order to generate the~e decoding representative levels the dynamic range DR and the minimum value MIN are supplied to the local decoders 124~ 127. Also, two-bit digitization codes lOO), (01), (10) and (11) are supplied from terminals 120, 121, 122 and 123, respectively~ The local decoders 124~ 127 and 128 comprise RONs to which the dynamic range DR and digitization code DT are supplied as addresses. The minimum value MIN is added to the data read out of the ~ONs.
The decoding level X10 of the reference pixel is formed by a local decoder 128 and a delay circuits 129 having the delay amount DL2 of one frame ~`
period. A digitization data DT from the code selecting circuit 115 is supplied to a local decoder 128. A decoding level of the objective pixel is generated from the local decoder 128. By passing the decoding level through a delay circuit 129, the decoding le~el xlO of the reference pixel is obtained. ` `
The decoding level is supplied to the subtracting circuits 116- 119. Therefore, the signals ~ 00 to ~ 0~ which are respectively generated from the subtracting circuits 116~ 119 correspond to the predictive difference between the four decodinq :;
- 2 2 - i ,,', :.
......
.: .
1324435 :;
representative levels and the decoding level X10 of . .
the preceding pixel as will be shown below, 00 = (I0 ~ MIN) - X10 '' 01 = ( Il ~ MIN ) - Xl 0 . ` -~ 02 = (I2 ~ MIN~ - X10 a 03 = (I3 ~ MIN) - X10 In the subtracting circuits 110~ 113, the ~.-following output signals are formed. :
T O = ~ t - ~ 00 r 1 = ~ t - ~ 01 r 2 = ~ t _ A 02 T 3 = ~ t - ~ 03 .
Since the minimu~ one o r 0- T 3 iS
detected by the minimum~alue detecting circuit 114, the digitization code of which the predictive change = is closest to tha true value of the change . ~: amount ~ t of the true value is selected by the code ~ .
selecting circuit 115. ` ~ `
Accordlng to the second embodiment, time `` ~
: ~ .
~ dependent change of the original image signai can be ., .
preserved so that the generation of the visually ~ : ; conspicuous noises in the rèconstructed image can be ~ : .. .
~ 2 3 - : ~:
. .
:: ` . ~'`':"' 1324~3~
prevented.
However, according to the first embodiment in which the spatial signal change can be preserved, the generation of the noises in the time direction cannot be prevented~ On the other hand, according to the second embodiment in which the time dependent -:
signal change can be preserved, the generation of the spatial noises cannot be prevented. Noreover, the digitiziny system in which such signal changes are `
significant has a problem such that errors are accumulated.
Therefore, in the third embodiment, a highly efficient coding apparatus which can be adapted preferably to the characteristics such as pattern, movement amount of a picture, and the like of an image ``
and which can improve the picture quality of the reconstructed image visually will be described hereinbelow with reference to Fig. 8~ ~:
In Fig. 8, a digital video signal in which, for instance, one pixel (one sample) is digitized to .
eight bits is supplied to an input terminal shown by "
reference numeral 201. The order of the data of the " :
input digital video signal is changed from the ~ ~.
scanning order to the order of blocks by a block ..
segmentation circuit 202. .
Since the circuits 203, 204 and 206 have the . ;
- 2 4 - ` ;. :
''"''~ ~' 24~3~
same construction as the circuit~ ~, 4 and 5 in Fig. 4, the detailed description of those is omitted, The output signal of the block segmentation circuit 202 is supplied to input terminals 211, 221 and 231 of a distortion detecting circuit 208, an inner space change detecting circuit 209, and a time dependent change detecting circuit 210 through a delay circuit 207. A delay amount DLl of the delay circuit 207 corresponds to the time necessary to detect the maximum and minimum values.
The distortion detecting circuit 208 is the first aritbmetic operating circuit for respectively arithmetically operating differences ~ 0, ~ 2 and ~ 3 between a true value xl of the objective pixel and four decoding representative vatues corresponding to the number of bits. The decodinq representative ~-values are formed by local decoders 241, 242, 243 and ` `
2~. Digitisation codes (00), (01), (10) and (11) each consisting of two bits are supplied from tarminals 245, 2~6, 2~7 and 248 to the local decoders 2~1 to 2~, respectively. In addition, the dynamic range DR and the minimum value MIN are supplied to the local decoders 241 to 244. The distortion detecting circuit 208 has input terminals 212, 213, 214 and 215 to which the above decoding representative values are respectively supplied and output terminals 217, 218, :: ~, ` '.'.. "`
- 2 5 - ` -:. .
132~435 219 and 220 to which the output signals ~ 0 to ~ 3 are extracted.
The inner space chanqe detecting circuit 209 is the second arithmetic operating circuit for calculating a spatial first change amount ~ r from the true value of the objective pixel and the true value of a peripheral pixel which spatially locates in the periphery, for calculating spatial second change amounts ~ 0, ~ 1, A 2 and ~ 3 from the decoding value of the digitization code of the peripheral pixel and the decoding representative values, and for calculating dif~erences ~ 0, ~ 2 and ~ 3 between the first change amount ~ r and the second change .
amounts ~ 0 to ~ 3. The inner space change detecting circuit 209 has input terminals 222, 223, 224 and 225 .
to which the above decoding representative values are " :
respectively supplied, an input terminal 226 to which .
th~ decoded value of the digitization code DT is supplied, and output terminals 227, 228, 229 and 230 to which the differences ~ 0 to ~ 3 are extracted. ` ;
The decoded value of the digitization code DT is formed by a local decoder 257. The dynamic range DR, the minimum value MIN, and the digitization . :~
code DT are supplied to the local decoder 257 and the . --.
level correspondinq to the digitization code DT is reconstructed by the decoding of the ADRC. The local . .
- 2 6 - .:
''' `"''"'''' '~' 1324~3~ -decoders 241, 244 and 257 comprise ROMs to which the dynamic range DR and digitization code are supplied as addresses. The minimum value MIN is added to the data read out of the ROMs.
The time dependent change detecting circuit 210 is the third arithmetic operating circuit for calculating a time dependent third change amount ~ t from the true value of the objective pixel and a true value of a reference pixel which is time precedent to the objective pixel and spatially corresponds thereto, for calculating time dependent fourth change amounts ~ 00, ~ 01, ^ 02 and ^ 03 ~rom the decoded value of the dig~itization code of the reference pixel and the `.
decoding representative values, and for calculating :.
differences T 0, T 1, T 2 and T 3 between the third change amount ~ t and the fourth change amounts ~ 00.` :
to ~ 03. The time dependent change detecting circuit 220 has input terminals 232, 233, 234 and 235 to which the above decoding representative values are respectively supplied, an input terminal 236 to which the decoded value of the digitization code is supplied, and output terminals 237, 238, 239 and 24Q to .
which the o~tput sign:als T O to T 3 are extracted.
Respective output signals of the distortion ; : detecting circuit 208, inner space change detecting circuit 209, and time dependent change detecting : ,, - 2 7 :
' .;
1~2~43~
circuit 210 are synthesized by weighting adding circuits 251, 252, 253 and 254. That is, the differential signals with respect to each of the four decoding representative values are weighted and added.
Assuming that wO, wl, w2 and w3 denote weighting -coefficients, the weighting adding circuit 251 generates a synthesized output ~ 0 which is expressed as follows.
`' ` `.
wO~ 0 ~ wl~ 0 + w2r 0 = ~ 0 ', ' In a manner similar to the above, the weighting adding ` `
circuits 252, 253 and 2S~ generate synthesized outputs ~ 2 and ~ 3 which are expressed as ~ollows. `
., wO~ 1 ~ wlP l ~ w2r l = ~ l ~
wO ~r 2 ~ Wl ~? 2 ~ W2 T 2 = &` 2 - ~ ~
wO~ 3 ~ wl~ 3 ~ w2r 3 = ~ 3 ```
Fixed values or variable values may be used ~ ;
as the weighting coe~ficients wO to w2 and they are .-; . . -set in consideration of the characteristics of the . . .
input image or the like. `
The synthesized outputs ~ 1 to ~ 3 from the -" '.`.
''''.` `''"' ``
., , . ~ . .
weighting adding circuits 251 to 254 are supplied to a minimum value detecting circuit 255. The minimum value detecting circuit 255 generates a detecti~n signal indicative of the minimum one of the synthesized outputs ~ 1 to ~ 3 . The detection signal is supplied to a code selecting circuit 256.
The digitization code DT of two bits which is specified by the detection signal is generated from the code selecting circuit 256. The digitization code DT is transmitted through the frame segmentation circuit 205~ That is, in the code selecting circuit 256, one of the two-bit digiti2ation codes (00), (01), "
~lO) and (11) corresponding to the decoding representative levels I0, Il, I2 and I3 is selected.
The selecting operation of the code selecting circuit 256 is as follows~ ``
When ~ O is minimum, (00~ is selected as the digitization code DT.
When ~ 1 is minimum, (01) is selected as the digitisation code DT.
When ~ 2 is minimum, (10) is selected as the digitisation code DT.
When ~ ~ is minimum, ~11) is selected as `
the digitization code DT. .:
Although not shown, on the reception side, :
the reception data is supplied to a frame - 2 9 - :
,..
~324~35 desegmentation circuit and the dynamic range DR, the minimum value MIN, and the digitization code DT are sepatated by the frame desegmentation eircuit. The dynamic range DR and the digitization code DT are supplied to the ROMS. The decoding level after the minimum value was eliminated is formed. The minimum value NIN is added to the decoding level. Further, the reconstruction levels obtained as the results of the addition are changed to the original scanning order by a block separating circuit. ~-As shown in Fig. 9, the distortion detecting `:
circuit 208 comprises subtracting circuits 261, 262, 263 and 26~. The true value xl of the objective pixel is commonly supplied from the input terminal 211 to `
the subtracting circuits 261 to 264, respectively. -O~ the other hand, the decoding representative levels tNIN ~ I0),tMIN ~ Il), (MIN ~ I2) and ~MIN ~ I3) are supplied from the input terminals 212 to 215 to the `` `
subtracting circuits 261 to 264, respectively~ `
Therefore, the following output signals a 0 to a 3 ~. -are obtained at the output terminals 217 to 220 of the subtracting circiuts 261 to 264, respectively.
R 0 = tI0 ~ NIN) - xl -1 = ~I1 ~ MIN) - xl 2 = tl2 ~ MIN) - xl .. ..
' ' :.:", - 3 0 - ;
"' :, a 3 = ( I 3 ~ MIN ) - Xl The output signals ~ 0 to ~ 3 of the above distortion detecting circuit 208 indicate the differences between the true value xl of the objective pixel and the decoding representative levels. The two-bit digitization code corresponding to the minimum one of the ~ 0 to ~ 3 expresses xl by the minimum distortion (the S/N ratio is best).
The inner space change detecting circuit 209 has a construction corresponding to that shown in Fig. ~. Similarly the construction of the time dependent change detecting circuit 210 corresponds to that shown in Fig~ 7. ~here~ore, the detailed description of these circuits 209 and 210 is omitted, ~ ; .
respectively. -~
he third embodiment is adapted to the `
cbaracteristics such as pattern, movement amount, and ; the like of the original image signal and the S/N
r~ r~t~o càn be improved. The`spatial change or time dependent change of tbe original image signal can be preserved, so that the generation of the visually `
conspicuous noises in the reconstructed image can be -prevented. ~ ~~
aving described a specific preferred embodiment of the present invention with reference to ^; ~; :
, , . .
~ "~C
1324~35 the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or the spirit of the invention as defined in the appended claims.
'`^"'`'`~ "",' ' `~,''`'`' `', .
'', - 3 2 - .. .
Claims (6)
1. A highly efficient coding apparatus for coding original digital video data having n bits for each picture element to provide compressed video data having the number of bits less than n for each picture element, comprising:
first detecting means for detecting a first difference between an original digital value of a first picture element to be encoded and an original digital value of a spatially adjacent picture element of said first picture element, first local decoding means for decoding encoded video data of said spatially adjacent picture element to generate a first decoded value, and generating means for generating compressed encoded video data of said first picture element wherein a difference between a decoded value of said compressed encoded video data and said first decoded value is closest to said first difference.
first detecting means for detecting a first difference between an original digital value of a first picture element to be encoded and an original digital value of a spatially adjacent picture element of said first picture element, first local decoding means for decoding encoded video data of said spatially adjacent picture element to generate a first decoded value, and generating means for generating compressed encoded video data of said first picture element wherein a difference between a decoded value of said compressed encoded video data and said first decoded value is closest to said first difference.
2. A highly efficient coding apparatus according to Claim l, wherein said generating means includes second local decoding means for decoding all compressed code data and for generating decoded values, first subtracting means for subtracting said first decoded value from each of said decoded value to generate first subtracted values, second subtracting means for subtracting each of said first subtracted values from said first difference to generate second subtracted values, minimum detecting means supplied with said second subtracted values and for detecting a minimum value thereof and code selecting means for selecting one of compressed code data corresponding to said detected minimum value.
3. A highly efficient coding apparatus according to Claim 1, wherein said digital video data are in the form of blocks of digital video data representing a plurality of picture elements.
4. A highly efficient coding apparatus according to Claim 3, wherein said first local decoding means includes first and second detecting means for detecting maximum and minimum values, respectively, of the digital video data representing the plurality of picture elements in each of said blocks, means for generating dynamic range information for each said block from said maximum and minimum values for the respective block, read only memory means supplied with said encoded video data of said spatially adjacent picture element and the dynamic range information and for generating code data having n bits, and adder means for adding said code data and said minimum value to generate said first decoded value.
5. A highly efficient coding apparatus for coding original digital video data having n bits for each picture element to provide compressed video data having the number of bits less than n for each picture element, comprising:
first detecting means for detecting a first difference between an original value of a first picture element to be encoded and an original digital value of a timely adjacent and spatially identical picture element of said first picture element, first local decoding means for decoding encoded video data of said timely adjacent and spatially identical picture element to generate a first decoded value, and generating means for generating compressed encoded video data of said first picture element wherein a difference between a decoded value of said compressed encoded video data and said first decoded value is closest to said first difference.
first detecting means for detecting a first difference between an original value of a first picture element to be encoded and an original digital value of a timely adjacent and spatially identical picture element of said first picture element, first local decoding means for decoding encoded video data of said timely adjacent and spatially identical picture element to generate a first decoded value, and generating means for generating compressed encoded video data of said first picture element wherein a difference between a decoded value of said compressed encoded video data and said first decoded value is closest to said first difference.
6. A highly efficient coding apparatus for coding original digital video data having n bits for each picture element to provide compressed video data having the number of bits less than n for each picture element, comprising:
first local decoding means for decoding all compressed code data and for generating decoded values for a first picture element to be encoded, first detecting means for detecting first differences between an original digital value of said first picture element and said each of said decoded values, second detecting means for detecting second differences between a difference value of the original digital value of said first picture element and an original digital value of spatially adjacent picture element of said first element and difference values of said decoded values and a decoded value of an encoded data of said spatially adjacent picture element, third detecting means for detecting third differences between a difference value of the original digital value of said first picture element and an original digital value of timely adjacent and spatially identical picture element of said first element and difference values of said decoded values and a decoded value of an encoded data of said timely adjacent and spatially identical picture element, weighting and adding means for multiplying first, second and third weighting coefficients to said first, second and third differences, respectively and for adding corresponding ones of the multiplied first, second and third differences together to generate added values, minimum detecting means supplied with said added values and for detecting a minimum value thereof, and code selecting means for selecting one of compressed code data corresponding to said minimum value.
first local decoding means for decoding all compressed code data and for generating decoded values for a first picture element to be encoded, first detecting means for detecting first differences between an original digital value of said first picture element and said each of said decoded values, second detecting means for detecting second differences between a difference value of the original digital value of said first picture element and an original digital value of spatially adjacent picture element of said first element and difference values of said decoded values and a decoded value of an encoded data of said spatially adjacent picture element, third detecting means for detecting third differences between a difference value of the original digital value of said first picture element and an original digital value of timely adjacent and spatially identical picture element of said first element and difference values of said decoded values and a decoded value of an encoded data of said timely adjacent and spatially identical picture element, weighting and adding means for multiplying first, second and third weighting coefficients to said first, second and third differences, respectively and for adding corresponding ones of the multiplied first, second and third differences together to generate added values, minimum detecting means supplied with said added values and for detecting a minimum value thereof, and code selecting means for selecting one of compressed code data corresponding to said minimum value.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP245228/88 | 1988-09-29 | ||
| JP24523088A JP2621422B2 (en) | 1988-09-29 | 1988-09-29 | Image data quantization circuit |
| JP245229/88 | 1988-09-29 | ||
| JP24522888A JP2606319B2 (en) | 1988-09-29 | 1988-09-29 | Image data quantization circuit |
| JP245230/88 | 1988-09-29 | ||
| JP24522988A JP2621421B2 (en) | 1988-09-29 | 1988-09-29 | Image data quantization circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1324435C true CA1324435C (en) | 1993-11-16 |
Family
ID=27333332
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000612054A Expired - Fee Related CA1324435C (en) | 1988-09-29 | 1989-09-20 | Highly efficient coding apparatus |
Country Status (4)
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|---|---|
| US (1) | US4953023A (en) |
| EP (1) | EP0368460B1 (en) |
| CA (1) | CA1324435C (en) |
| DE (1) | DE68917260T2 (en) |
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Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US32291A (en) * | 1861-05-14 | Henry s | ||
| US3502815A (en) * | 1967-03-17 | 1970-03-24 | Xerox Corp | Tone signalling bandwidth compression system |
| JPS587109B2 (en) * | 1974-09-09 | 1983-02-08 | ケイディディ株式会社 | Fukushima Shingo no Jiyouhou Hen Kagaso Address Fugoukahoushiki |
| GB2050752B (en) * | 1979-06-07 | 1984-05-31 | Japan Broadcasting Corp | Motion compensated interframe coding system |
| JPS5954376A (en) * | 1982-09-21 | 1984-03-29 | Konishiroku Photo Ind Co Ltd | Picture processing method |
| US4442454A (en) * | 1982-11-15 | 1984-04-10 | Eastman Kodak Company | Image processing method using a block overlap transformation procedure |
| US4701807A (en) * | 1983-09-22 | 1987-10-20 | Canon Kabushiki Kaisha | Method and apparatus for processing an image |
| US4558370A (en) * | 1983-11-21 | 1985-12-10 | International Business Machines Corporation | Image processing method for graphics images |
| JPS61114677A (en) * | 1984-11-09 | 1986-06-02 | Nec Corp | Adaptability prediction coding decoding system and device for animation signal |
| KR910000707B1 (en) * | 1986-05-26 | 1991-01-31 | 미쓰비시덴기 가부시기가이샤 | Method and apparatus for encoding transmitting |
| US5123059A (en) * | 1987-09-28 | 1992-06-16 | Dainippon Screen Mfg. Co., Ltd. | Gradation converting circuit employing lookup table |
-
1989
- 1989-09-15 US US07/407,753 patent/US4953023A/en not_active Expired - Lifetime
- 1989-09-20 CA CA000612054A patent/CA1324435C/en not_active Expired - Fee Related
- 1989-09-25 DE DE68917260T patent/DE68917260T2/en not_active Expired - Fee Related
- 1989-09-25 EP EP89309707A patent/EP0368460B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0368460A1 (en) | 1990-05-16 |
| DE68917260D1 (en) | 1994-09-08 |
| EP0368460B1 (en) | 1994-08-03 |
| US4953023A (en) | 1990-08-28 |
| DE68917260T2 (en) | 1995-02-23 |
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