Image coding method and image decoding method

• US 20040032908A1
• Filed: 05/06/2003
• Published: 02/19/2004
• Est. Priority Date: 09/12/2001
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kadono, Shinya, Hagai, Makoto
• Granted Patent: US 7,126,989 B2
• Time in Patent Office: Days
• US Class Current: 375/240.25
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/156 Availability of hardware or computational resources, e.g. encoding based on power-saving criteria
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/527 Global motion vector estimation
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

A picture coding apparatus (300) is a picture coding apparatus that codes a difference between picture data (Img) representing an input picture and predictive picture data (Pred) representing a predictive picture for the input picture and generates coded picture data, and includes a picture decoding unit (104) for decoding coded picture data (Img) after the picture data (Img) is coded; inter pixel filters A and B (303 and 304) for performing inter pixel filter operation for decoded picture data (Recon) obtained by the picture decoding unit (104); switches (301 and 302) for selecting one of the inter pixel filters; and an inter picture predicting unit (108) for generating the predictive picture data (Pred) for the input picture data (Img) using filtered decoded picture data (FilteredImg1), as reference picture data (Ref), obtained by the selected inter pixel filter.

Claims

1. A picture coding method for coding differential picture data that is a difference between input picture data representing an input picture and predictive picture data representing a predictive picture for a picture in the input picture, so as to generate coded picture data, the picture coding method comprising:

a decoding step for decoding the coded differential picture data and adding the decoded differential picture data and the predictive picture data, after the differential picture data is coded;

a selecting step for selecting one of a plurality of inter pixel filters;

a filtering step for performing an inter pixel filtering for the decoded picture data obtained in the decoding step, using the selected inter pixel filter; and

a predictive picture generating step for generating the predictive picture data for the input picture data using the filtered decoded picture data, as reference picture data, obtained in the filtering step.

2. The picture coding method according to claim 1, further comprising an output data generating step for generating output coded picture data for outside output based on the coded picture data and relevant data which is relevant to said coded picture data,

wherein in the output data generating step, selection information specifying the inter pixel filter selected in the selecting step is described in the relevant data.

3. The picture coding method according to claim 1,

wherein in the selecting step, an inter pixel filter with higher smoothing level is selected if the input picture data is a picture which is referred to by another picture.

4. The picture coding method according to claim 3,

wherein whether or not the input picture data is the picture which is referred to by said another picture is judged depending on a picture type of the input picture data.

5. A picture coding method for coding differential picture data that is a difference between input picture data representing an input picture and predictive picture data representing a predictive picture for a picture in the input picture, so as to generate coded picture data, the picture coding method comprising:

a decoding step for decoding the coded differential picture data and adding the decoded differential picture data and the predictive picture data, after the differential picture data is coded;

a selecting step for selecting whether or not an inter pixel filtering is to be performed;

a filtering step for performing the filtering for the decoded picture data obtained in the decoding step, using an inter pixel filter, if it is selected that the filtering is to be performed, and not performing the filtering if it is selected that the filtering is not to be performed; and

a predictive picture generating step for generating the predictive picture data for the input picture data using the decoded picture data, as reference picture data, obtained in the filtering step.

6. The picture coding method according to claim 5, further comprising an output data generating step for generating output coded picture data for outside output based on the coded picture data and relevant data which is relevant to said coded picture data,

wherein in the output data generating step, selection information specifying an inter pixel filter selected in the selecting step is described in the relevant data.

7. The picture coding method according to claim 5,

wherein in the selecting step, an inter pixel filter with higher smoothing level is selected if the input picture data is a picture which is referred to by another picture.

8. The picture coding method according to claim 5,

wherein in the selecting step, the filter is selected depending on a picture type of the input picture data.

9. The picture coding method according to claim 5,

wherein in the selecting step, it is selected that the filtering is not performed if the input picture data is a B-picture.

10. The picture coding method according to claim 5,

wherein the inter pixel filter is an arithmetic filter which operates variably according to a value of an inputted parameter.

11. The picture coding method according to claim 5,

wherein in the selecting step, an inter pixel filter is selected as a result of switching in the unit of predetermined data in the input picture data.

12. A picture decoding method for decoding coded picture data, comprising:

a decoding step for decoding the coded picture date to generate differential picture data and adding predictive picture data and the differential picture data to generate picture data representing an original picture;

a selecting step for selecting one of a plurality of inter pixel filters;

a filtering step for performing an inter pixel filtering for the picture data representing the original picture decoded in the decoding step, using the selected inter pixel filter; and

a predictive picture generating step for generating the predictive picture data from the picture data which is performed of the filtering.

13. The picture decoding method according to claim 12, further comprising a determining step for determining whether or not there is a possibility that the coded picture data is referred to, depending on a picture type of the coded picture data,

wherein in the selecting step, an inter pixel filter with higher smoothing level is selected if the coded picture data is a picture which is referred to by another picture.

14. The picture decoding method according to claim 12,

wherein in the decoding step, relevant information which is relevant to the coded picture data is further decoded, and

in the selecting step, the inter pixel filter is selected according to the decoded relevant information.

15. The picture decoding method according to claim 14,

wherein in the selecting step, when the inter pixel filter which is indicated in the decoded relevant information is not included in a picture decoding apparatus, an inter pixel filter whose smoothing level is approximate to smoothing level of the inter pixel filter indicated in the relevant information is selected from among the inter pixel filters included in the picture decoding apparatus.

16. The picture decoding method according to claim 14,

wherein in the selecting step, a bypass line for bypassing the inter pixel filters is included in the plurality of inter pixel filters as one inter pixel filter, and

in the predictive picture generating step, when the bypass line is selected, the predictive picture data is generated from the decoded picture data which is not performed of the filtering.

17. The picture decoding method according to claim 16, further comprising:

a second filtering step for performing a second inter pixel filtering for the decoded picture data which is not performed of the filtering, when the bypass line is selected in the filtering step; and

an outputting step for outputting to the outside, as output picture data, the decoded picture data which is performed of the second inter pixel filtering.

18. The picture decoding method according to claim 16,

in the selecting step, an inter pixel filter is selected as a result of switching in the unit of predetermined data in the coded picture data.

19. The picture decoding method according to claim 16,

wherein the inter pixel filter is an arithmetic filter which operates variably according to a value of a parameter.

20. A picture coding apparatus that codes differential picture data that is a difference between input picture data representing an input picture and predictive picture data representing a predictive picture for a picture in the input picture, so as to generate coded picture data, the picture coding apparatus comprising:

a decoding unit operable to decode the coded differential picture data and add the decoded differential picture data and the predictive picture data, after the differential picture data is coded;

a plurality of inter pixel filters for performing an inter pixel filtering for the decoded picture data obtained by the decoding unit;

a selecting unit operable to select one of the plurality of inter pixel filters; and

a predictive picture generating unit operable to generate the predictive picture data for the input picture data, using the filtered decoded picture data, as reference picture data, obtained by the selected inter pixel filter.

21. The picture coding apparatus according to claim 20, further comprising a bypass line for bypassing the plurality of inter pixel filters,

wherein the selecting unit selects one of any of the inter pixel filters and the bypass line.

22. The picture coding apparatus according to claim 21, further comprising an output data generating unit operable to generate output coded picture data for outside output based on the coded picture data and relevant data which is relevant to said coded picture data,

wherein the output data generating unit describes in the relevant data selection information specifying one of any of the inter pixel filters and the bypass line which is selected by the selecting unit.

23. The picture coding apparatus according to claim 21,

wherein the selecting unit selects an inter pixel filter with higher smoothing level if the input picture data is a picture which is referred to by another picture.

24. The picture coding apparatus according to claim 21,

wherein the selecting unit selects one of an inter pixel filter involving light processing load and the bypass line if the input picture data is a picture which is not referred to by another picture or the input picture data is a B-picture.

25. The picture coding apparatus according to claim 24,

wherein the selecting unit selects one of the inter pixel filter involving light processing load and the bypass line if the input picture data is a B-picture.

26. The picture coding apparatus according to claim 20,

wherein the inter pixel filter is an arithmetic filter which operates variably according to a parameter.

27. The picture coding apparatus according to claim 20,

wherein the selecting unit selects an inter pixel filter as a result of switching in the unit of predetermined data in the input picture data.

28. A picture decoding apparatus that decodes coded picture data obtained by coding a difference between picture data representing a picture in original moving pictures and predictive picture data representing another picture in the original moving pictures to generate a plurality of picture data representing the original moving pictures, the picture decoding apparatus comprising:

a decoding unit operable to add the decoding result of the coded picture data and the already decoded predictive picture data associated with the coded picture data to generate picture data representing an original picture;

a selecting unit operable to select one of a plurality of inter pixel filters for performing an inter pixel filtering for the decoded picture data; and

a predictive picture generating unit operable to generate the predictive picture data associated with another coded picture data from the picture data which is performed of the filtering by the selected inter pixel filter.

29. The picture decoding apparatus according to claim 28, further comprising a determining unit operable to determine whether or not there is a possibility that the coded picture data is referred to, depending on a picture type of the coded picture data,

wherein the selecting unit selects an inter pixel filter with higher smoothing level if the coded picture data is a picture which is referred to by another picture.

30. The picture decoding apparatus according to claim 28,

wherein the decoding unit further decodes relevant information of the coded picture data, and

the selecting unit selects the inter pixel filter according to the decoded relevant information.

31. The picture decoding apparatus according to claim 30,

wherein when the inter pixel filter which is indicated in the decoded relevant information is not included in the picture decoding apparatus, the selecting unit selects an inter pixel filter whose smoothing level is approximate to smoothing level of the inter pixel filter indicated in the relevant information from among the inter pixel filters included in the picture decoding apparatus.

32. The picture decoding apparatus according to claim 30, further comprising a bypass line for bypassing the plurality of inter pixel filters as one of the plurality of inter pixel filters,

wherein when the bypass line is selected, the predictive picture generating unit generates the predictive picture data from the decoded picture data which is not performed of the filtering.

33. The picture decoding apparatus according to claim 32, further comprising:

a second inter pixel filter for performing a second inter pixel filtering for the decoded picture data which is not performed of the filtering when the bypass line is selected; and

an outputting unit operable to output to the outside, as output picture data, the decoded picture data which is performed of the second inter pixel filtering.

34. A program for a picture coding apparatus that codes differential picture data that is a difference between input picture data representing an input picture and predictive picture data representing a predictive picture for a picture in the input picture, so as to generate coded picture data, the program causing a computer to function as:

a decoding unit operable to decode the coded differential picture data and add the decoded differential picture data and the predictive picture data, after the differential picture data is coded,;

a plurality of inter pixel filters for performing an inter pixel filtering for the decoded picture data obtained by the decoding unit;

a selecting unit operable to select one of the plurality of inter pixel filters; and

a predictive picture generating unit operable to generate the predictive picture data for the input picture data using the filtered decoded picture data, as reference picture data, obtained by the inter pixel filter.

35. A program for a picture decoding apparatus that decodes coded picture data obtained by coding a difference between picture data representing a picture in original moving pictures and predictive picture data representing another picture in the original moving pictures to generate a plurality of picture data representing the original moving pictures, the program causing a computer to function as:

a decoding unit operable to add the decoding result of the coded picture data and the already decoded predictive picture data associated with the coded picture data to generate picture data representing an original picture;

a selecting unit operable to select one of a plurality of inter pixel filters for performing an inter pixel filtering for the decoded picture data; and

a predictive picture generating unit operable to generate the predictive picture data associated with another coded picture data from the picture data which is performed of the filtering by the selected inter pixel filter.

36. A computer readable recording medium on which coded picture data and relevant data of the coded picture data are recorded,

wherein information is recorded on the recording medium, the information specifying, from among a plurality of inter pixel filterings, an inter pixel filtering which should be performed for decoded picture data in decoding the coded picture data to use the decoded picture data as a reference picture, in the unit of predetermined data in the coded picture data.

37. A computer readable recording medium on which coded picture data and relevant data of the coded picture data are recorded,

wherein information is recorded on the recording medium, the information indicating whether or not an inter pixel filtering should be performed for decoded picture data in decoding the coded picture data to use the decoded picture data as a reference picture, in the unit of predetermined data in the coded picture data.

38. A picture coding apparatus that codes pictures which are inputted in sequence, the picture coding apparatus comprising:

a coding unit operable to code a picture by performing predetermined transformation processing for the picture;

an inverse transformation unit operable to perform inverse transformation processing to the transformation processing for the picture coded by the coding unit;

a filtering unit operable to perform filtering for the picture;

a memorizing unit operable to memorize the picture; and

a controlling unit operable to perform control so as to store the picture obtained by the inverse transformation processing by the inverse transformation unit in the memorizing unit after the filtering is performed by the filtering unit, or to store the picture in the memorizing unit without the filtering being performed by the filtering unit,

wherein the coding unit codes the picture with reference to a past picture which has been stored in the memorizing unit.

39. The picture coding apparatus according to claim 38,

wherein the controlling unit performs control so as to perform the filtering when a significance level of the picture is high, and not to perform the filtering when the significance level of the picture is low.

40. The picture coding apparatus according to claim 39,

wherein the coding unit performs coding including intra picture coding and inter picture coding for the picture, and

the controlling unit judges that the significance level of the picture is high and performs control so as to perform the filtering for the picture when the picture is intra picture coded by the coding unit, and judges that the significance level of the picture is low and performs control so as not to perform the filtering for the picture when the picture is inter picture coded by the coding unit.

41. The picture coding apparatus according to claim 39,

wherein the coding unit performs coding including forward predictive coding and bi-predictive coding, and

the controlling unit judges that the significance level of the picture is high and performs control so as to perform the filtering for the picture when the picture is forward predictive coded by the coding unit, and judges that the significance level of the picture is low and performs control so as not to perform the filtering for the picture when the picture is bi-predictive coded by the coding unit.

42. The picture coding apparatus according to claim 39,

wherein the coding unit performs coding including base layer coding and enhancement layer coding, and

the controlling unit judges that the significance level of the picture is high and performs control so as to perform the filtering for the picture when the picture is base layer coded by the coding unit, and judges that the significance level of the picture is low and performs control so as not to perform the filtering for the picture when the picture is enhancement layer coded by the coding unit.

43. The picture coding apparatus according to claim 39,

wherein the controlling unit monitors whether or not the picture coding apparatus has enough processing capacity, and performs control so as to perform the filtering for pictures including pictures with lower significance levels if the picture coding apparatus has enough processing capacity, and not to perform the filtering for pictures including pictures with higher significance levels if the picture coding apparatus does not have enough processing capacity.

44. The picture coding apparatus according to claim 43,

wherein a priority corresponding to the significance level is associated with the picture, and

the controlling unit monitors an operation rate of a CPU included in the picture coding apparatus to monitor the processing capacity, and performs control so as to perform the filtering for only the pictures with higher priorities if the operation rate is high, and not to perform the filtering for the pictures including the pictures with lower priorities if the operation rate is low.

45. The picture coding apparatus according to claim 44,

wherein the picture belongs to any of a plurality of types,

the controlling unit has a first information table and a second information table, the first information table associating the type of the picture with the priority, and the second information table indicating a combination between the priority and the operation rate for performing the filtering;

determines a priority of a picture to be coded, with reference to the first information table based on the type of said picture; and

determines whether or not the filtering is to be performed for the picture, with reference to the second information table based on a combination between the determined priority and the operation rate.

46. The picture coding apparatus according to claim 45,

wherein the controlling unit has a plurality of the first information tables and a plurality of the second information tables;

determines the priority of the picture with reference to one first information table selected from among the plurality of the first information tables; and

determines whether or not the filtering is to be performed for the picture, with reference to one second information table selected from the plurality of the second information tables.

47. A picture decoding apparatus that decodes pictures which are inputted in sequence, the picture coding apparatus comprising:

a decoding unit operable to decode a picture by performing predetermined transformation processing for the picture;

a filtering unit operable to perform filtering for the picture;

a memorizing unit operable to memorize the picture; and

a controlling unit operable to perform control so as to store the picture obtained by the decoding by the decoding unit in the memorizing unit after the filtering is performed by the filtering unit, or to store the picture in the memorizing unit without the filtering being performed by the filtering unit,

wherein the decoding unit decodes the picture with reference to a past picture which has been stored in the memorizing unit.

48. The picture decoding apparatus according to claim 47,

wherein the controlling unit performs control so as to perform the filtering when a significance level of the picture is high, and not to perform the filtering when the significance level of the picture is low.

49. The picture decoding apparatus according to claim 48,

wherein the decoding unit performs decoding including intra picture decoding and inter picture decoding for the picture, and

the controlling unit judges that the significance level of the picture is high and performs control so as to perform the filtering for the picture when the picture is intra picture decoded by the decoding unit, and judges that the significance level of the picture is low and performs control so as not to perform the filtering for the picture when the picture is inter picture decoded by the decoding unit.

50. The picture decoding apparatus according to claim 48,

wherein the decoding unit performs decoding including forward predictive decoding and bi-predictive decoding, and

the controlling unit judges that the significance level of the picture is high and performs control so as to perform the filtering for the picture when the picture is forward predictive decoded by the decoding unit, and judges that the significance level of the picture is low and performs control so as not to perform the filtering for the picture when the picture is backward predictive decoded by the decoding unit.

51. The picture decoding apparatus according to claim 48,

wherein the decoding unit performs decoding including base layer decoding and enhancement layer decoding, and

the controlling unit judges that the significance level of the picture is high and performs control so as to perform the filtering for the picture when the picture is base layer decoded by the decoding unit, and judges that the significance level of the picture is low and performs control so as not to perform the filtering for the picture when the picture is enhancement layer decoded by the decoding unit.

52. The picture decoding apparatus according to claim 48,

wherein the controlling unit monitors whether or not the picture decoding apparatus has enough processing capacity, and performs control so as to perform the filtering for pictures including pictures with lower significance levels if the picture coding apparatus has enough processing capacity, and not to perform the filtering for pictures including pictures with higher significance levels if the picture coding apparatus does not have enough processing capacity.

53. The picture decoding apparatus according to claim 52,

wherein a priority corresponding to the significance level is associated with the picture, and

the controlling unit monitors an operation rate of a CPU included in the picture decoding apparatus to monitor the processing capacity, and performs control so as to perform the filtering for only the pictures with higher priorities if the operation rate is high, and not to perform the filtering for the pictures including the pictures with lower priorities if the operation rate is low.

54. The picture decoding apparatus according to claim 53,

wherein the picture belongs to any of a plurality of types,

the controlling unit has a first information table and a second information table, the first information table associating the type of the picture with the priority, and the second information table indicating a combination between the priority and the operation rate for performing the filtering;

determines a priority of a picture to be decoded, with reference to the first information table based on the type of said picture; and

determines whether or not the filtering is to be performed for the picture, with reference to the second information table based on a combination between the determined priority and the operation rate.

55. The picture decoding apparatus according to claim 54,

wherein the controlling unit has a plurality of the first information tables and a plurality of the second information tables;

determines the priority of the picture with reference to one first information table selected from among the plurality of the first information tables; and

determines whether or not the filtering is to be performed for the picture, with reference to one second information table selected from the plurality of the second information tables.

56. A picture coding method for performing coding with reference to a picture obtained by performing filtering for a coded picture,

wherein when a significance level of a picture to be coded is high, the filtering is performed for the picture after coding, and when the significance level of the picture is low, the filtering is not performed for the picture after coding.

57. A picture decoding method for performing decoding with reference to a picture obtained by performing filtering for a decoded picture,

wherein when a significance level of a picture to be decoded is high, the filtering is performed for the picture after decoding, and when the significance level of the picture is low, the filtering is not performed for the picture after decoding.