CA2328581C - Method for the coding of picture signals - Google Patents
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- CA2328581C CA2328581C CA 2328581 CA2328581A CA2328581C CA 2328581 C CA2328581 C CA 2328581C CA 2328581 CA2328581 CA 2328581 CA 2328581 A CA2328581 A CA 2328581A CA 2328581 C CA2328581 C CA 2328581C
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Abstract
A hybrid Discrete Cosine Transform (DCT) coder processes blocks of (e.g., 8X8) pixels from interlaced or progressive scanned image signals. Processing of image lines by the coder is modified in the presence of image motion to avoid switching between 8X8 and 2X(4X8) transformations. For motion, the lines of two vertically superimposed image blocks are rearranged to produce first and second modified blocks.
The modified first block contains pixels from lines in a first field, and the modified second block contains pixels from lines in an associated adjacent second field.
The modified first block contains pixels from lines in a first field, and the modified second block contains pixels from lines in an associated adjacent second field.
Description
Method for the coding of picture signals This application is a divisional of Canadian patent application serial number 2,108,778 filed on April 14, 1992.
The invention relates to a method for the coding of picture signals.
BACKGROUND OF THE INVENTION
This invention relates to a system for coding image signals such as by means of a DCT (Discrete Cosine Transform), for example.
A transformation circuit for facilitating an 8*8 or a 2*(4*8) DCT transformation is described in DE 36 42 664. Switching between an 8*8 and a 2*(4*8) DCT may be accomplished in response to the state of a logic level on a control line.
SUMMARY OF THE INVENTION
An object of the invention is to provide a system for coding image signals by means of a codec suitable for processing both progressively scanned and interlace scanned image signals.
In a system according to the present invention, before coding with a hybrid coder which can process blocks of progressively scanned picture elements (pixels), line sections from respective blocks of interlace scanned picture elements within two vertically superimposed blocks are arranged such that only line sections from one field of an image signal are contained within each of these blocks.
1a Image motion is detected and the line sections are re-sorted within the superimposed blocks in the presence of dynamic image content.
According to a method for hybrid coding of image signals proposed by ISO-MPEG (International Organisation for Standardization, Motion Picture Expert Group) under Standard Proposal number ISO 11172, progressively scanned input signals are DCT processed in blocks, whereby respective blocks of 8*8 picture elements are coded or decoded and a sequence of inter-frame coded images is replaced as regular intervals by intra-frame coded images. The effectiveness of the coding is also a function of the relatively high spatial correlation of picture elements within such blocks. If interlaced source signals are to be processed by such a hybrid decoded, coding effectiveness decreases if dynamic image content or the data rate required for coding increases. This results because every second line derives from a block having different phases of motion, and correlation of picture elements within such a block decrease.
In contrast, coding effectiveness is maintained in the presence of a static image. With a dynamic image, image lines associated with a first field from two superimposed 8*8 picture element blocks are now combined into a first 8*8 block, and lines associated with a corresponding second field from these two superimposed 8*8 picture element blocks are combined into a second 8*8 block, and are applied in this form to the hybrid coder.
Due to such reorganisation of the input signals, it is not necessary to switch between 8*8 and a 2*(4*8) DCT
transformation in the hybrid coder as in DE 36 42 664.
Instead, an 8*8 DCT can also be advantageously performed for a dynamic image.
A motion detector indicates whether a static of dynamic image is present, and re-sorting or addressing of the lines is done accordingly. Such motion information may be added to the coded data for the respective block by means of a bit per block or double block. During decoding, the corresponding lines are arranged in the original sequence whereby the motion information is evaluated. According to the MPEG standard, four luminance picture element blocks arranged in the shape of a square are combined into a macroblock. Advantageously, two of the superimposed blocks of such a macroblock form a pair in the above-mentioned sense. Accordingly, one bit per macroblock can indicate the resorting.
The invention may be summarized according to one aspect as method for the coding of picture signal pixel blocks having a predetermined size, including a transform using a hybrid coder, wherein the original picture signal has interlace format, the method including the steps: a) in a first mode, re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size, so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks; b) in a second mode, not carrying out such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size, in order to keep a high spatial correlation between pixels in the pixels blocks; c) DCT
transforming the square shape pixel blocks of said predetermined size resulting from steps a) or b); d) coding the picture signal, thereby adding to the picture signal 3a additional items of information indicating whether a re-sorting or re-addressing of the line sections according to step a) has taken place in corresponding pixel blocks;
wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
According to another aspect the invention provides method for the decoding of transformed and coded picture signal pixel blocks, wherein the pixel blocks of an original interlace format picture signal were coded in a hybrid coder and thereby a modified processing took place in a first mode, and wherein in a first mode re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size took place so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks, and wherein in a second mode such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size was not carried out in order to keep a high spatial correlation between pixels in the pixel blocks, the method including the decoding steps: - inverse transforming coded square shape blocks of a predetermined size to provide corresponding square shape pixel blocks having said predetermined size;
3b square shape pixel blocks having said predetermined size;
- evaluating additional items of information that are included in the coded picture signal to be decoded, said additional items of information indicating whether said first or said second mode was carried out in the coding;
- in the case of said additional items of information indicating that said first mode is to be carried out for corresponding pixel blocks, re-sorting or re-addressing pixel block line sections within two vertically adjacent square shape pixel blocks each having said predetermined size, so that within each of these two pixel blocks alternating line sections from both field types of said interlace format picture signal are contained, wherein one of these two pixel blocks when input for said inverse transforming contained only line sections from one field type of said interlace format picture signal and the other block when input for said inverse transforming contained only line sections from the other field type of said interlace format picture signal; - in the case of said additional items of information indicating that said second mode is to be carried out, not re-sorting or re-addressing the line sections in corresponding pixel blocks, wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
According to a further aspect the invention provides a coded digital signal containing coded data for picture signal pixel blocks having a predetermined size, the 3c transform in a hybrid coder, wherein the original picture signal data input to said coding had interlace format, the coded digital signal having the following properties: a) in a first mode for square shape macroblock data contained in said coded digital signal, line section data of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size are in a re-sorted format, so that one of these two pixel blocks contains line section data from only one field type of said interlace format original picture signal and the other block contains line section data from only the other field type of said interlace format original picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted pixels blocks; b) in a second mode for square shape macroblock data contained in said coded digital signal, no such re-sorted format of line section data of the pixel blocks having said predetermined size is present, in order to keep a high spatial correlation between pixels in the pixels blocks; c) the data for the square shape pixel blocks of said predetermined size according to features a) or b) are transformed coded data, wherein said coded digital signal contains in addition items of information indicating whether a re-sorted format according to feature a) is present in corresponding macroblocks, and wherein in each case four square shape luminance blocks of said predetermined size form a macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in such macroblocks of said coded digital signal.
3d BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the location of image lines within blocks for static (a) and dynamic (b) images.
FIG. 2 is a block diagram codec apparatus in accordance with the invention.
FIGS. 3 and 4 are flow diagrams respectively depicting encoder and decoder processing methods in accordance with the principles of the invention.
FIG. la and FIG. lb respectively show two superimposed blocks of luminance or chrominance picture elements in the x-y plane. For simplicity of illustration, the blocks each have a size of 4*4 picture elements instead of a size of 8*8 picture elements. In general, the blocks could also have a size of (2*n)*(2*m) where n = 1, 2, 3, . . ., m = 1, 2, 3, . . ., instead of 8*8. The two digit numbers respectively mark the spatial position of a picture element. The first digit of this number represents the block number, the second, the line number within a block.
The picture elements of the known hybrid coder which are to be coded or decoded in progressively scanned form are arranged in accordance with FIG. la. This likewise applies for picture elements having static picture content for interlace scanned picture elements. Before the coding in the case of dynamic picture content, the lines of two superimposed blocks are interchanged in accordance with FIG.
lb and after the decoding, they are re-arranged in accordance with FIG. la.
3e FIG. 2 shows a hybrid coder 25 corresponding to the aforesaid Standard Proposal. Interlace scanned picture signals from picture n are supplied to the input 21 and thence arrive in a picture store 22 and a movement detector 24. The items of data (two superimposed blocks) of picture n-1 needed by the movement detector 24 and the line sections of the respective two blocks involved are read out from the picture store 22 into a block store 23, from which the hybrid coder is able to select 8*8 blocks on each occasion. The picture elements for static picture content corresponding to Fig. 1a and those for dynamic picture content corresponding to Fig. lb are buffer stored in the block store 23.
The movement detector can be realised in accordance with various known methods. For example, the absolute value differences of picture elements from blocks having the same spatial position of picture n and picture n-1 may be formed for each block or double block that has to be coded. Alternatively, movement vectors (e.g. for two superimposed blocks on each occasion) formed by the hybrid coder 25 can be used instead of the movement detector. If the instantaneous sum of these absolute value differences and/or the amount of the corresponding movement vectors for this block or these blocks exceeds a predetermined threshold (i.e. dynamic picture content is involved), the picture elements corresponding to Fig. lb, otherwise those corresponding to Fig. la, are buffer stored in the block store 23.
The re-sorting may be undertaken in accordance with the following listing:
DO.y = 1, N/2 DO x = 1,N
Houtl(x~Y) - Binl(x~2*Y-1) Houtl(x~Y) - Binl(x~2*Y) ENDDO
ENDDO
DO y = 1,N/2 DO x = 1,N
Boutl(x~y+N/2) - Bin2(x~2*y-1) Houtl(x~Y+N/2) - Bin2(x~2*Y) ENDDO
ENDDO, wherein, Bins is the block located in the higher position and N
is an even number.
FIG. 3 is a flow chart illustrating a method as described above in accordance with the principles of the 5 invention. In method step 30 an input signal is evaluated to determine if it exhibits interlaced or progressive scan form.
A progressive scan signal is transformed and coded without further processing at step 32 via node 31. If an interlaced signal is detected at step 30, the interlaced signal is evaluated at step 34 to determine if it contains motion. If it does not, the interlaced signal is coupled via step 36 without rearranging its original line structure to step 32 where the interlaced signal is transformed and coded. If step 34 senses that the interlaced signal contains motion, the processing of step 36 is controlled so as to rearrange the line structure of the interlaced signal (as previously discussed). The interlaced signal with rearranged line structure is transformed and subsequently coded by step 32. In step 38 a control signal indicating a rearranged line structure when an interlaced signal with motion is detected is provided to the coding function in step 32. The coding function in step 32 may provide a motion vector to motion detection step 34 to indicate a motion condition for rearranging the line structure of an interlaced signal. Picture and block storage steps as may be required to facilitate the process illustrated by FIG. 3 have been discussed previously in connection with FIG. 2 and have not been shown to simplify FIG. 3.
FIG. 4 is a flowchart illustrating decoder processing steps associated with the coding process discussed in connection with FIG. 3. An input signal transform coded as 5a discussed previously is decoded and inverse transformed by step 40. Before being applied to an output, the decoded signal is processed by a step 42, which rearranges the line structure back to an original structure if the signal exhibits an interlaced line format with motion. For this purpose step 44 determines if the input signal exhibits an interlaced line structure. If it does, step 46 determines if the interlaced signal contains motion. If motion is detected, a control signal is provided to step 42 to effect rearranging of the lines of the interlaced signal back to an original structure.
The invention relates to a method for the coding of picture signals.
BACKGROUND OF THE INVENTION
This invention relates to a system for coding image signals such as by means of a DCT (Discrete Cosine Transform), for example.
A transformation circuit for facilitating an 8*8 or a 2*(4*8) DCT transformation is described in DE 36 42 664. Switching between an 8*8 and a 2*(4*8) DCT may be accomplished in response to the state of a logic level on a control line.
SUMMARY OF THE INVENTION
An object of the invention is to provide a system for coding image signals by means of a codec suitable for processing both progressively scanned and interlace scanned image signals.
In a system according to the present invention, before coding with a hybrid coder which can process blocks of progressively scanned picture elements (pixels), line sections from respective blocks of interlace scanned picture elements within two vertically superimposed blocks are arranged such that only line sections from one field of an image signal are contained within each of these blocks.
1a Image motion is detected and the line sections are re-sorted within the superimposed blocks in the presence of dynamic image content.
According to a method for hybrid coding of image signals proposed by ISO-MPEG (International Organisation for Standardization, Motion Picture Expert Group) under Standard Proposal number ISO 11172, progressively scanned input signals are DCT processed in blocks, whereby respective blocks of 8*8 picture elements are coded or decoded and a sequence of inter-frame coded images is replaced as regular intervals by intra-frame coded images. The effectiveness of the coding is also a function of the relatively high spatial correlation of picture elements within such blocks. If interlaced source signals are to be processed by such a hybrid decoded, coding effectiveness decreases if dynamic image content or the data rate required for coding increases. This results because every second line derives from a block having different phases of motion, and correlation of picture elements within such a block decrease.
In contrast, coding effectiveness is maintained in the presence of a static image. With a dynamic image, image lines associated with a first field from two superimposed 8*8 picture element blocks are now combined into a first 8*8 block, and lines associated with a corresponding second field from these two superimposed 8*8 picture element blocks are combined into a second 8*8 block, and are applied in this form to the hybrid coder.
Due to such reorganisation of the input signals, it is not necessary to switch between 8*8 and a 2*(4*8) DCT
transformation in the hybrid coder as in DE 36 42 664.
Instead, an 8*8 DCT can also be advantageously performed for a dynamic image.
A motion detector indicates whether a static of dynamic image is present, and re-sorting or addressing of the lines is done accordingly. Such motion information may be added to the coded data for the respective block by means of a bit per block or double block. During decoding, the corresponding lines are arranged in the original sequence whereby the motion information is evaluated. According to the MPEG standard, four luminance picture element blocks arranged in the shape of a square are combined into a macroblock. Advantageously, two of the superimposed blocks of such a macroblock form a pair in the above-mentioned sense. Accordingly, one bit per macroblock can indicate the resorting.
The invention may be summarized according to one aspect as method for the coding of picture signal pixel blocks having a predetermined size, including a transform using a hybrid coder, wherein the original picture signal has interlace format, the method including the steps: a) in a first mode, re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size, so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks; b) in a second mode, not carrying out such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size, in order to keep a high spatial correlation between pixels in the pixels blocks; c) DCT
transforming the square shape pixel blocks of said predetermined size resulting from steps a) or b); d) coding the picture signal, thereby adding to the picture signal 3a additional items of information indicating whether a re-sorting or re-addressing of the line sections according to step a) has taken place in corresponding pixel blocks;
wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
According to another aspect the invention provides method for the decoding of transformed and coded picture signal pixel blocks, wherein the pixel blocks of an original interlace format picture signal were coded in a hybrid coder and thereby a modified processing took place in a first mode, and wherein in a first mode re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size took place so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks, and wherein in a second mode such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size was not carried out in order to keep a high spatial correlation between pixels in the pixel blocks, the method including the decoding steps: - inverse transforming coded square shape blocks of a predetermined size to provide corresponding square shape pixel blocks having said predetermined size;
3b square shape pixel blocks having said predetermined size;
- evaluating additional items of information that are included in the coded picture signal to be decoded, said additional items of information indicating whether said first or said second mode was carried out in the coding;
- in the case of said additional items of information indicating that said first mode is to be carried out for corresponding pixel blocks, re-sorting or re-addressing pixel block line sections within two vertically adjacent square shape pixel blocks each having said predetermined size, so that within each of these two pixel blocks alternating line sections from both field types of said interlace format picture signal are contained, wherein one of these two pixel blocks when input for said inverse transforming contained only line sections from one field type of said interlace format picture signal and the other block when input for said inverse transforming contained only line sections from the other field type of said interlace format picture signal; - in the case of said additional items of information indicating that said second mode is to be carried out, not re-sorting or re-addressing the line sections in corresponding pixel blocks, wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
According to a further aspect the invention provides a coded digital signal containing coded data for picture signal pixel blocks having a predetermined size, the 3c transform in a hybrid coder, wherein the original picture signal data input to said coding had interlace format, the coded digital signal having the following properties: a) in a first mode for square shape macroblock data contained in said coded digital signal, line section data of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size are in a re-sorted format, so that one of these two pixel blocks contains line section data from only one field type of said interlace format original picture signal and the other block contains line section data from only the other field type of said interlace format original picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted pixels blocks; b) in a second mode for square shape macroblock data contained in said coded digital signal, no such re-sorted format of line section data of the pixel blocks having said predetermined size is present, in order to keep a high spatial correlation between pixels in the pixels blocks; c) the data for the square shape pixel blocks of said predetermined size according to features a) or b) are transformed coded data, wherein said coded digital signal contains in addition items of information indicating whether a re-sorted format according to feature a) is present in corresponding macroblocks, and wherein in each case four square shape luminance blocks of said predetermined size form a macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in such macroblocks of said coded digital signal.
3d BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the location of image lines within blocks for static (a) and dynamic (b) images.
FIG. 2 is a block diagram codec apparatus in accordance with the invention.
FIGS. 3 and 4 are flow diagrams respectively depicting encoder and decoder processing methods in accordance with the principles of the invention.
FIG. la and FIG. lb respectively show two superimposed blocks of luminance or chrominance picture elements in the x-y plane. For simplicity of illustration, the blocks each have a size of 4*4 picture elements instead of a size of 8*8 picture elements. In general, the blocks could also have a size of (2*n)*(2*m) where n = 1, 2, 3, . . ., m = 1, 2, 3, . . ., instead of 8*8. The two digit numbers respectively mark the spatial position of a picture element. The first digit of this number represents the block number, the second, the line number within a block.
The picture elements of the known hybrid coder which are to be coded or decoded in progressively scanned form are arranged in accordance with FIG. la. This likewise applies for picture elements having static picture content for interlace scanned picture elements. Before the coding in the case of dynamic picture content, the lines of two superimposed blocks are interchanged in accordance with FIG.
lb and after the decoding, they are re-arranged in accordance with FIG. la.
3e FIG. 2 shows a hybrid coder 25 corresponding to the aforesaid Standard Proposal. Interlace scanned picture signals from picture n are supplied to the input 21 and thence arrive in a picture store 22 and a movement detector 24. The items of data (two superimposed blocks) of picture n-1 needed by the movement detector 24 and the line sections of the respective two blocks involved are read out from the picture store 22 into a block store 23, from which the hybrid coder is able to select 8*8 blocks on each occasion. The picture elements for static picture content corresponding to Fig. 1a and those for dynamic picture content corresponding to Fig. lb are buffer stored in the block store 23.
The movement detector can be realised in accordance with various known methods. For example, the absolute value differences of picture elements from blocks having the same spatial position of picture n and picture n-1 may be formed for each block or double block that has to be coded. Alternatively, movement vectors (e.g. for two superimposed blocks on each occasion) formed by the hybrid coder 25 can be used instead of the movement detector. If the instantaneous sum of these absolute value differences and/or the amount of the corresponding movement vectors for this block or these blocks exceeds a predetermined threshold (i.e. dynamic picture content is involved), the picture elements corresponding to Fig. lb, otherwise those corresponding to Fig. la, are buffer stored in the block store 23.
The re-sorting may be undertaken in accordance with the following listing:
DO.y = 1, N/2 DO x = 1,N
Houtl(x~Y) - Binl(x~2*Y-1) Houtl(x~Y) - Binl(x~2*Y) ENDDO
ENDDO
DO y = 1,N/2 DO x = 1,N
Boutl(x~y+N/2) - Bin2(x~2*y-1) Houtl(x~Y+N/2) - Bin2(x~2*Y) ENDDO
ENDDO, wherein, Bins is the block located in the higher position and N
is an even number.
FIG. 3 is a flow chart illustrating a method as described above in accordance with the principles of the 5 invention. In method step 30 an input signal is evaluated to determine if it exhibits interlaced or progressive scan form.
A progressive scan signal is transformed and coded without further processing at step 32 via node 31. If an interlaced signal is detected at step 30, the interlaced signal is evaluated at step 34 to determine if it contains motion. If it does not, the interlaced signal is coupled via step 36 without rearranging its original line structure to step 32 where the interlaced signal is transformed and coded. If step 34 senses that the interlaced signal contains motion, the processing of step 36 is controlled so as to rearrange the line structure of the interlaced signal (as previously discussed). The interlaced signal with rearranged line structure is transformed and subsequently coded by step 32. In step 38 a control signal indicating a rearranged line structure when an interlaced signal with motion is detected is provided to the coding function in step 32. The coding function in step 32 may provide a motion vector to motion detection step 34 to indicate a motion condition for rearranging the line structure of an interlaced signal. Picture and block storage steps as may be required to facilitate the process illustrated by FIG. 3 have been discussed previously in connection with FIG. 2 and have not been shown to simplify FIG. 3.
FIG. 4 is a flowchart illustrating decoder processing steps associated with the coding process discussed in connection with FIG. 3. An input signal transform coded as 5a discussed previously is decoded and inverse transformed by step 40. Before being applied to an output, the decoded signal is processed by a step 42, which rearranges the line structure back to an original structure if the signal exhibits an interlaced line format with motion. For this purpose step 44 determines if the input signal exhibits an interlaced line structure. If it does, step 46 determines if the interlaced signal contains motion. If motion is detected, a control signal is provided to step 42 to effect rearranging of the lines of the interlaced signal back to an original structure.
Claims (10)
1. ~Method for the coding of picture signal pixel blocks having a predetermined size, including a transform using a hybrid coder, wherein the original picture signal has interlace format, the method including the steps:
a) in a first mode, re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size, so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks;
b) in a second mode, not carrying out such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size, in order to keep a high spatial correlation between pixels in the pixels blocks;
c) DCT transforming the square shape pixel blocks of said predetermined size resulting from steps a) or b);
d) coding the picture signal, thereby adding to the picture signal additional items of information indicating whether a re-sorting or re-addressing of the line sections according to step a) has taken place in corresponding pixel blocks;
wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
a) in a first mode, re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size, so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks;
b) in a second mode, not carrying out such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size, in order to keep a high spatial correlation between pixels in the pixels blocks;
c) DCT transforming the square shape pixel blocks of said predetermined size resulting from steps a) or b);
d) coding the picture signal, thereby adding to the picture signal additional items of information indicating whether a re-sorting or re-addressing of the line sections according to step a) has taken place in corresponding pixel blocks;
wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
2. ~Method according to claim 1, wherein the pixel blocks have a predetermined size of 8*8 pixels.
3. Method according to claim 1 or 2, wherein said modes are controlled by the output signal of a movement detector or by movement vectors generated in said hybrid coder.
4. Method according to claim 1 or 2, wherein for the determination of said modes for each of the pixel blocks or vertically adjacent double pixel blocks to be coded the differences between the absolute pixel values from pixel blocks of the same spatial position of two successive pictures are formed, such that, if a current sum of the absolute pixel value differences for a current pixel block or double pixel block exceeds a predetermined threshold, said re-sorting or re-addressing of the line sections takes place.
5. Method for the decoding of transformed and coded picture signal pixel blocks, wherein the pixel blocks of an original interlace format picture signal were coded in a hybrid coder and thereby a modified processing took place in a first mode, and wherein in a first mode re-sorting or re-addressing line sections of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size took place so that one of these two pixel blocks contains only line sections from one field type of said interlace format picture signal and the other block contains only line sections from the other field type of said interlace format picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted or re-addressed pixels blocks, and wherein in a second mode such re-sorting or re-addressing of line sections of the pixel blocks having said predetermined size was not carried out in order to keep a high spatial correlation between pixels in the pixel blocks, the method including the decoding steps:
- inverse transforming coded square shape blocks of a predetermined size to provide corresponding square shape pixel blocks having said predetermined size;
- evaluating additional items of information that are included in the coded picture signal to be decoded, said additional items of information indicating whether said first or said second mode was carried out in the coding;
- in the case of said additional items of information indicating that said first mode is to be carried out for corresponding pixel blocks, re-sorting or re-addressing pixel block line sections within two vertically adjacent square shape pixel blocks each having said predetermined size, so that within each of these two pixel blocks alternating line sections from both field types of said interlace format picture signal are contained, wherein one of these two pixel blocks when input for said inverse transforming contained only line sections from one field type of said interlace format picture signal and the other block when input for said inverse transforming contained only line sections from the other field type of said interlace format picture signal;
- in the case of said additional items of information indicating that said second mode is to be carried out, not re-sorting or re-addressing the line sections in corresponding pixel blocks, wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
- inverse transforming coded square shape blocks of a predetermined size to provide corresponding square shape pixel blocks having said predetermined size;
- evaluating additional items of information that are included in the coded picture signal to be decoded, said additional items of information indicating whether said first or said second mode was carried out in the coding;
- in the case of said additional items of information indicating that said first mode is to be carried out for corresponding pixel blocks, re-sorting or re-addressing pixel block line sections within two vertically adjacent square shape pixel blocks each having said predetermined size, so that within each of these two pixel blocks alternating line sections from both field types of said interlace format picture signal are contained, wherein one of these two pixel blocks when input for said inverse transforming contained only line sections from one field type of said interlace format picture signal and the other block when input for said inverse transforming contained only line sections from the other field type of said interlace format picture signal;
- in the case of said additional items of information indicating that said second mode is to be carried out, not re-sorting or re-addressing the line sections in corresponding pixel blocks, wherein in each case four square shape luminance blocks of said predetermined size are combined in a square shape macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in a macroblock.
6. Method according to claim 5, wherein said transform is a DCT transform and said inverse transform is an inverse DCT transform.
7. Method according to claim 5 or 6, wherein the pixel blocks have a predetermined size of 8*8 pixels.
8. A coded digital signal containing coded data for picture signal pixel blocks having a predetermined size, the data of which pixel blocks were coded with the help of a transform in a hybrid coder, wherein the original picture signal data input to said coding had interlace format, the coded digital signal having the following properties:
a) in a first mode for square shape macroblock data contained in said coded digital signal, line section data of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size are in a re-sorted format, so that one of these two pixel blocks contains line section data from only one field type of said interlace format original picture signal and the other block contains line section data from only the other field type of said interlace format original picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted pixels blocks;
b) in a second mode for square shape macroblock data contained in said coded digital signal, no such re-sorted format of line section data of the pixel blocks having said predetermined size is present, in order to keep a high spatial correlation between pixels in the pixels blocks;
c) the data for the square shape pixel blocks of said predetermined size according to features a) or b) are transformed coded data, wherein said coded digital signal contains in addition items of information indicating whether a re-sorted format according to feature a) is present in corresponding macroblocks, and wherein in each case four square shape luminance blocks of said predetermined size form a macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in such macroblocks of said coded digital signal.
a) in a first mode for square shape macroblock data contained in said coded digital signal, line section data of the pixel blocks within two vertically adjacent square shape pixel blocks each having said predetermined size are in a re-sorted format, so that one of these two pixel blocks contains line section data from only one field type of said interlace format original picture signal and the other block contains line section data from only the other field type of said interlace format original picture signal, in order to achieve a high spatial correlation between pixels in the re-sorted pixels blocks;
b) in a second mode for square shape macroblock data contained in said coded digital signal, no such re-sorted format of line section data of the pixel blocks having said predetermined size is present, in order to keep a high spatial correlation between pixels in the pixels blocks;
c) the data for the square shape pixel blocks of said predetermined size according to features a) or b) are transformed coded data, wherein said coded digital signal contains in addition items of information indicating whether a re-sorted format according to feature a) is present in corresponding macroblocks, and wherein in each case four square shape luminance blocks of said predetermined size form a macroblock and two block pairs from said vertically adjacent pixel blocks are included in such macroblock, each one of said additional items of information in each case being valid in common for the four luminance blocks included in such macroblocks of said coded digital signal.
9. ~~Coded digital signal according to claim 8, wherein said transform is a DCT transform.
10. ~Coded digital signal according to claim 8 or 9, wherein the pixel blocks have a predetermined size of 8*8 pixels.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4113505.9 | 1991-04-25 | ||
| DE4113505A DE4113505A1 (en) | 1991-04-25 | 1991-04-25 | METHOD FOR IMAGE SIGNAL CODING |
| CA002108778A CA2108778C (en) | 1991-04-25 | 1992-04-14 | Process for coding picture signals |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002108778A Division CA2108778C (en) | 1991-04-25 | 1992-04-14 | Process for coding picture signals |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2328581A1 CA2328581A1 (en) | 1992-10-26 |
| CA2328581C true CA2328581C (en) | 2002-02-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2328581 Expired - Lifetime CA2328581C (en) | 1991-04-25 | 1992-04-14 | Method for the coding of picture signals |
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| Country | Link |
|---|---|
| CA (1) | CA2328581C (en) |
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- 1992-04-14 CA CA 2328581 patent/CA2328581C/en not_active Expired - Lifetime
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| Publication number | Publication date |
|---|---|
| CA2328581A1 (en) | 1992-10-26 |
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