Methods and apparatus for implicit and semi-implicit intra mode signaling for video encoders and decoders

1. An apparatus, comprising:

an encoder for encoding picture data for at least a portion of a picture, wherein said encoder derives an intra mode to apply to the portion from neighboring template data and abstains from explicitly signaling the intra mode for the portion, the neighboring template data corresponding to a neighboring template formed from neighboring pixels with respect to the portion, and

wherein the intra mode for the portion is implicitly derived from a subset of a set of available intra modes, and not an entirety of the set, by

using the neighboring template data to test a particular intra mode within the subset based upon a least distortion measure from among respective distortion measures,

said least distortion measure being performed for a particular intra mode between predicted values and said neighboring template data,

wherein the predicted values and said neighboring template data correspond to a candidate neighborhood with respect to the portion;

and wherein said neighboring template comprises a neighboring patch with respect to said portion, and

wherein said neighboring patch includes already decoded pixels.

2. The apparatus of claim 1 , wherein the intra mode for the portion is implicitly derived using the neighboring template data to test a subset of a set of available intra modes and not an entirety of the set, and a particular intra mode within the subset is selected as the intra mode for the portion based upon a least distortion measure.

3. The apparatus of claim 2 , wherein the least distortion measure is determined based upon a sum of absolute difference or a mean square error.

4. The apparatus of claim 2 , wherein the subset is determined based upon a function of intra modes used for neighboring blocks.

5. The apparatus of claim 2 , wherein the intra mode for the portion is further implicitly derived as a function of intra modes for the neighboring blocks and a best mode for the neighboring template.

6. The apparatus of claim 5 , wherein the best mode for the neighboring template is determined by testing several or all intra modes used for the neighboring template, and selecting a given intra mode providing a least distortion measure, from among the several or all intra modes used for the neighboring template, as the best mode for the neighboring template.

7. The apparatus of claim 5 , wherein the function is a median function.

8. The apparatus of claim 1 , wherein an implicit intra mode derivation is performed for a subset of blocks in a picture, while an explicit intra mode signaling is performed for the other blocks in the picture, the subset of blocks being the portion.

9. In a video encoder, a method, comprising:

encoding picture data for at least a portion of a picture by deriving an intra mode to apply to the portion from neighboring template data; and

abstaining from explicitly signaling the intra mode for the portion,

wherein the neighboring template data corresponds to a neighboring template formed from neighboring pixels with respect to the portion, and

wherein the intra mode for the portion is implicitly derived from a subset of a set of available intra modes, and not an entirety of the set, by

using the neighboring template data to test a particular intra mode within the subset based upon a least distortion measure from among respective distortion measures,

said least distortion measure being performed for a particular intra mode between predicted values and said neighboring template data,

wherein the predicted values and said neighboring template data correspond to a candidate neighborhood with respect to the portion;

and wherein said neighboring template comprises a neighboring patch with respect to said portion, and

wherein said neighboring patch includes already decoded pixels.

10. The method of claim 9 , wherein the intra mode for the portion is implicitly derived using the neighboring template data to test a subset of a set of available intra modes and not an entirety of the set, and a particular intra mode within the subset is selected as the intra mode for the portion based upon a least distortion measure.

11. The method of claim 10 , wherein the least distortion measure is determined based upon a sum of absolute difference or a mean square error.

12. The method of claim 10 , wherein the subset is determined based upon a function of intra modes used for neighboring blocks.

13. The method of claim 10 , wherein the intra mode for the portion is further implicitly derived as a function of intra modes for the neighboring blocks and a best mode for the neighboring template.

14. The method of claim 13 , wherein the best mode for the neighboring template is determined by testing several or all intra modes used for the neighboring template, and selecting a given intra mode providing a least distortion measure, from among the several or all intra modes used for the neighboring template, as the best mode for the neighboring template.

15. The method of claim 13 , wherein the function is a median function.

16. The method of claim 9 , wherein an implicit intra mode derivation is performed for a subset of blocks in a picture, while an explicit intra mode signaling is performed for the other blocks in the picture, the subset of blocks being the portion.

17. An apparatus, comprising:

a decoder for decoding picture data for at least a portion of a picture, wherein said decoder derives an intra mode to apply to the portion from neighboring template data in an absence of receiving any explicit signaling of the intra mode for the portion, the neighboring template data corresponding to a neighboring template formed from neighboring pixels with respect to the portion, and

wherein the intra mode for the portion is implicitly derived from a subset of a set of available intra modes, and not an entirety of the set, by

using the neighboring template data to test a particular intra mode within the subset based upon a least distortion measure from among respective distortion measures,

said least distortion measure being performed for a particular intra mode between predicted values and said neighboring template data,

wherein the predicted values and said neighboring template data correspond to a candidate neighborhood with respect to the portion;

and wherein said neighboring template comprises a neighboring patch with respect to said portion, and

wherein said neighboring patch includes already decoded pixels.

18. The apparatus of claim 17 , wherein the intra mode for the portion is implicitly derived using the neighboring template data to test a subset of a set of available intra modes and not an entirety of the set, and a particular intra mode within the subset is selected as the intra mode for the portion based upon a least distortion measure.

19. The apparatus of claim 18 , wherein the least distortion measure is determined based upon a sum of absolute difference or a mean square error.

20. The apparatus of claim 18 , wherein the subset is determined based upon a function of intra modes used for neighboring blocks.

21. The apparatus of claim 18 , wherein the intra mode for the portion is further implicitly derived as a function of intra modes for the neighboring blocks and a best mode for the neighboring template.

22. The apparatus of claim 21 , wherein the best mode for the neighboring template is determined by testing several or all intra modes used for the neighboring template, and selecting a given intra mode providing a least distortion measure, from among the several or all intra modes used for the neighboring template, as the best mode for the neighboring template.

23. The apparatus of claim 21 , wherein the function is a median function.

24. The apparatus of claim 17 , wherein an implicit intra mode derivation is performed for a subset of blocks in a picture, while an explicit intra mode derivation is performed for the other blocks in the picture, the subset of blocks being the portion.

25. In a video decoder, a method, comprising:

decoding picture data for at least a portion of a picture by deriving an intra mode to apply to the portion from neighboring template data in an absence of receiving any explicit signaling of the intra mode for the portion,

wherein the neighboring template data corresponds to a neighboring template formed from neighboring pixels with respect to the portion, and

wherein the intra mode for the portion is implicitly derived from a subset of a set of available intra modes, and not an entirety of the set, by

using the neighboring template data to test a particular intra mode within the subset based upon a least distortion measure from among respective distortion measures,

said least distortion measure being performed for a particular intra mode between predicted values and said neighboring template data,

wherein the predicted values and said neighboring template data correspond to a candidate neighborhood with respect to the portion;

and wherein said neighboring template comprises a neighboring patch with respect to said portion, and

wherein said neighboring patch includes already decoded pixels.

26. The method of claim 25 , wherein the intra mode for the portion is implicitly derived using the neighboring template data to test a subset of a set of available intra modes and not an entirety of the set, and a particular intra mode within the subset is selected as the intra mode for the portion based upon a least distortion measure.

27. The method of claim 26 , wherein the least distortion measure is determined based upon a sum of absolute difference or a mean square error.

28. The method of claim 26 , wherein the subset is determined based upon a function of intra modes used for neighboring blocks.

29. The method of claim 26 , wherein the intra mode for the portion is further implicitly derived as a function of intra modes for the neighboring blocks and a best mode for the neighboring template.

30. The method of claim 29 , wherein the best mode for the neighboring template is determined by testing several or all intra modes used for the neighboring template, and selecting a given intra mode providing a least distortion measure, from among the several or all intra modes used for the neighboring template, as the best mode for the neighboring template.

31. The method of claim 29 , wherein the function is a median function.

32. The method of claim 25 , wherein an implicit intra mode derivation is performed for a subset of blocks in a picture, while an explicit intra mode derivation is performed for the other blocks in the picture, the subset of blocks being the portion.