Apparatus, a method and a computer program product for coding and decoding chroma components of texture pictures for sample prediction of depth pictures

1. A method comprising:

obtaining a depth view component map;

decoding one or both chroma components of a coded texture picture into one or two decoded chroma sample arrays;

obtaining a reference sample array on the basis of said one or two decoded chroma sample arrays by modifying said one or two decoded chroma sample arrays, said modifying comprising:

segmenting said one or two decoded chroma sample arrays, wherein said segmenting comprises creating a histogram of sample values of said one or two decoded chroma sample arrays;

replacing the sample values in each segment by a representative value of said each segment wherein the representative value is derived from comparing segments of the histogram sample values of said one or two decoded chroma sample arrays with sample values of one or more regions of the depth map and using the sample values of the depth region spatially overlapping a majority of samples of a chroma sample array segment as the values of respective samples in each segment; and

forming a decoded depth view component on the basis of said reference sample array.

2. The method according to claim 1 , the method further comprising

modifying said one or two decoded chroma sample arrays in order to obtain the reference sample array, said modifying comprising

partitioning said one or two decoded chroma sample arrays into blocks to be filtered;

deriving bands of sample values to be filtered for each block;

decoding an offset for each band and each block to be filtered; and

summing each sample value of a block to be filtered and the offset for the band for said each sample value.

3. The method according to claim 1 , the method further comprising

using at least one of said modified chroma sample arrays as a monochrome picture to be

used as a reference for sample prediction of the depth view.

4. The method according to claim 1 , the method further comprising

including a picture containing a processed chroma sample array in a reference picture list more than once with different associated weighting parameters.

5. An apparatus comprising:

at least one processor and at least one memory, said at least one memory stored with code thereon, which when executed by said at least one processor, causes an apparatus to perform at least:

obtaining a depth map;

decoding one or both chroma components of a coded texture picture into one or two decoded chroma sample arrays;

obtaining a reference sample array on the basis of said one or two decoded chroma sample arrays by modifying said one or two decoded chroma sample arrays in, said modifying comprising:

segmenting said one or two decoded chroma sample arrays, wherein said segmenting comprises creating a histogram of sample values of said one or two decoded chroma sample arrays; and

replacing the sample values in each segment by a representative value of said each segment, wherein the representative value is derived from comparing segments of the histogram sample values of said one or two decoded chroma sample arrays with sample values of one or more regions of the depth map and using the sample values of the depth region spatially overlapping a majority of samples of a chroma sample array segment as the values of respective samples in each segment; and

forming a decoded depth view component on the basis of said reference sample array.

6. The apparatus according to claim 5 , further comprising code, which when executed by said at least one processor, causes an apparatus to perform

modifying said one or two decoded chroma sample arrays in order to obtain the reference sample array, said modifying comprising

partitioning said one or two decoded chroma sample arrays into blocks to be filtered;

deriving bands of sample values to be filtered for each block;

decoding an offset for each band and each block to be filtered; and

summing each sample value of a block to be filtered and the offset for the band for said each sample value.

7. The apparatus according to claim 5 , further comprising code, which when executed by said at least one processor, causes an apparatus to perform

using at least one of said modified chroma sample arrays as a monochrome picture to be used as a reference for sample prediction of the depth view.

8. The apparatus according to claim 5 , further comprising code, which when executed by said at least one processor, causes an apparatus to perform

including a picture containing a processed chroma sample array in a reference picture list more than once with different associated weighting parameters.

9. A computer program product embodied on a non-transitory computer readable storage medium, comprising program code configured to, which when executed by a processor, causes an apparatus to perform:

obtaining a depth map;

decoding one or both chroma components of a coded texture picture into one or two decoded chroma sample arrays;

obtaining a reference sample array on the basis of said one or two decoded chroma sample arrays by modifying said one or two decoded chroma sample arrays, said modifying comprising:

segmenting said one or two decoded chroma sample arrays, wherein said segmenting comprises creating a histogram of sample values of said one or two decoded chroma sample arrays; and

replacing the sample values in each segment by a representative value of said each segment, wherein the representative value is derived from comparing segments of the histogram sample values of said one or two decoded chroma sample arrays with sample values of one or more regions of the depth map and using the sample values of the depth region spatially overlapping a majority of samples of a chroma sample array segment as the values of respective samples in each segment; and

forming a decoded depth view component on the basis of said reference sample array.

10. A method comprising:

encoding one or two chroma components of a texture picture into one or two coded chroma components and reconstructing one or two reconstructed chroma sample arrays;

obtaining a reference sample array on the basis of modifying said one or two reconstructed chroma sample arrays, said modifying comprising segmenting said one or two reconstructed chroma sample arrays by creating a histogram of sample values of said one or two reconstructed chroma sample arrays and comparing segments of the histogram sample values of said one or two decoded chroma sample arrays with sample values of one or more regions of a depth map and using the sample values of the depth region spatially overlapping a majority of samples of a chroma sample array segment as the values of respective samples in each segment; and

using the reference sample array as a reference for prediction in encoding of a depth view component.

11. The method according to claim 10 , the method further comprising

modifying said one or two reconstructed chroma sample arrays in order to obtain the reference sample array, said modifying comprising

partitioning said one or two reconstructed chroma sample arrays into blocks to be filtered;

deriving bands of sample values to be filtered for each block;

encoding an offset for each band and each block to be filtered; and

summing each sample value of a block to be filtered and the offset for the band for said each sample value.

12. The method according to claim 11 , the method further comprising

using at least one of said modified chroma sample arrays as a monochrome picture to be used as a reference for sample prediction of the depth view.

13. The method according to claim 10 , the method further comprising

including a picture containing a processed chroma sample array in a reference picture list more than once with different associated weighting parameters.

14. An apparatus comprising:

at least one processor and at least one memory, said at least one memory stored with code thereon, which when executed by said at least one processor, causes an apparatus to perform at least:

encoding one or two chroma components of a texture picture into one or two coded chroma components and reconstructing one or two reconstructed chroma sample arrays;

obtaining a reference sample array on the basis of modifying said one or two reconstructed chroma sample arrays, said modifying comprising segmenting said one or two reconstructed chroma sample arrays by creating a histogram of sample values of said one or two reconstructed chroma sample arrays and comparing segments of the histogram sample values of said one or two decoded chroma sample arrays with sample values of one or more regions of a depth map and using the sample values of the depth region spatially overlapping a majority of samples of a chroma sample array segment as the values of respective samples in each segment; and

using the reference sample array as a reference for prediction in encoding of a depth view component.

15. The apparatus according to claim 14 , further comprising code, which when executed by said at least one processor, causes the apparatus to perform:

modifying said one or two reconstructed chroma sample arrays in order to obtain the reference sample array, said modifying comprising

partitioning said one or two reconstructed chroma sample arrays into blocks to be filtered;

deriving bands of sample values to be filtered for each block;

encoding an offset for each band and each block to be filtered; and

summing each sample value of a block to be filtered and the offset for the band for said each sample value.

16. The apparatus according to claim 14 , further comprising code, which when executed by said at least one processor, causes the apparatus to perform

using at least one of said modified chroma sample arrays as a monochrome picture to be used as a reference for sample prediction of the depth view.

17. The apparatus according to claim 14 , further comprising code, which when executed by said at least one processor, causes the apparatus to perform

including a picture containing a processed chroma sample array in a reference picture list more than once with different associated weighting parameters.

18. A computer program product embodied on a non-transitory computer readable storage medium configured to, when executed by a processor, cause an apparatus to perform:

encoding one or two chroma components of a texture picture into one or two coded chroma components and reconstructing one or two reconstructed chroma sample arrays;

obtaining a reference sample array on the basis of modifying said one or two reconstructed chroma sample arrays, said modifying comprising segmenting said one or two reconstructed chroma sample arrays by creating a histogram of sample values of said one or two reconstructed chroma sample arrays and comparing segments of the histogram sample values of said one or two decoded chroma sample arrays with sample values of one or more regions of a depth map and using the sample values of the depth region spatially overlapping a majority of samples of a chroma sample array segment as the values of respective samples in each segment; and

using the reference sample array as a reference for prediction in encoding of a depth view component.