Adaptive partition coding
Although wedgelet-based partitioning seems to represent a better tradeoff between side information rate on the one hand and achievable variety in partitioning possibilities on the other hand, compared to contour partitioning, the ability to alleviate the constraints of the partitioning to the extent that the partitions have to be wedgelet partitions, enables applying relatively uncomplex statistical analysis onto overlaid spatially sampled texture information in order to derive a good predictor for the bi-segmentation in a depth/disparity map. Thus, in accordance with a first aspect it is exactly the increase of the freedom which alleviates the signaling overhead provided that co-located texture information in form of a picture is present. Another aspect pertains the possibility to save side information rate involved with signaling a respective coding mode supporting irregular partitioning.
1. A decoder for reconstructing a predetermined block of a depth/disparity map associated with a texture picture from a data stream, configured to:
determine a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segment the reference block of the texture picture by thresholding the texture picture within the reference block using the texture threshold to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transfer the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
decode the predetermined block in units of the first and second partitions.
2. The decoder according to claim 1 , configured to, in thresholding, individually check values of the texture picture within the reference block at tiles of a two-dimensional subdivision of the reference block, as to whether the respective value is greater than or lower than a respective predetermined value, so that each of the first and second partitions of the reference block of the texture picture is a set of the tiles which together completely cover the reference block of the texture picture and are complementary to each other.
3. The decoder according to claim 2 , configured to, in thresholding, individually check values of the texture picture within the reference block at sample resolution so that each tile corresponds to a sample position of the reference block.
4. The decoder according to claim 1 , configured to, in segmenting, apply morphological hole filling and/or low-pass filtering onto a result of the thresholding in order to acquire the bi-segmentation of the reference block into the first and second partitions.
5. The decoder according to claim 1 , configured to, in thresholding, determine a measure for a central tendency of reconstructed sample values of the reference block of the texture picture and perform the thresholding by comparing each reconstructed sample value of the reference block of the texture picture with a respective threshold which depends on the measure determined.
6. The decoder according to claim 1 , configured such that the segmentation, spatial transfer and prediction form one of a first set of coding options, which is not part of a second set of coding options, wherein the decoder is further configured to
determine a dispersion of value of samples within the reference block of the texture picture; and
receive a coding option identifier from the data stream, use the coding option identifier as an index into the first set of coding options in case of the dispersion exceeding a predetermined threshold, with performing the segmentation, spatial transfer and prediction onto the predetermined block if the index points to the one coding option, and as an index into the second set of coding options in case of the dispersion succeeding the predetermined threshold.
7. A decoder for reconstructing a predetermined block of a depth/disparity map associated with a texture picture from a data stream, configured to:
determine a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segment the reference block of the texture picture depending on a texture feature of the texture picture within the reference block using edge detection or by thresholding the texture picture using the texture threshold, so as to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transfer the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
decode the predetermined block in units of the first and second partitions,
wherein the decoder is configured such that the segmentation, spatial transfer and decoding form one of a first set of coding options of the decoder, which is not part of a second set of coding options of the decoder, wherein the decoder is further configured to
determine a dispersion of values of samples within the reference block of the texture picture; and
retrieve a coding option identifier from the data stream, use the coding option identifier as an index into the first set of coding options in case of the dispersion exceeding a predetermined threshold, with performing the segmentation, spatial transfer and decoding onto the predetermined block if the index points to the one coding option, and as an index into the second set of coding options in case of the dispersion succeeding the predetermined threshold.
8. The decoder according to claim 7 , wherein the decoder is configured to retrieve the coding option identifier by entropy decoding.
9. The decoder according to claim 1 , further configured to use the predetermined block as a reference in a prediction loop of the decoder.
10. The decoder according to claim 7 , further configured to use the predetermined block as a reference in a prediction loop of the decoder.
11. The decoder according to claim 1 , wherein the decoder is configured to, in decoding the predetermined block,
predict the predetermined block by assigning a first constant partition value to samples of the sample array positioned within the first partition and a second constant partition value to samples of the sample array positioned within the second partition.
12. The decoder according to claim 7 , wherein the decoder is configured to, in decoding the predetermined block,
predict the predetermined block by assigning a first constant partition value to samples of the sample array positioned within the first partition and a second constant partition value to samples of the sample array positioned within the second partition.
13. The decoder according to claim 12 , wherein the decoder is configured to, in predicting the predetermined block, associate each of neighboring samples of the sample array, adjoining to the predetermined block, with a respective one of the first and second partitions so that each neighboring sample adjoins the partition with which same is associated, and predict the predetermined block by assigning a mean value of values of the neighboring samples associated with the first partition to samples of the sample array positioned within the first partition and a mean value or values of the neighboring samples associated with the second partition to samples of the sample array positioned within the second partition.
14. The decoder according to claim 11 , configured to refine the prediction of the predetermined block by applying a first refinement value within the refinement information onto mean value of values of neighboring samples associated with the first partition, and/or applying a second refinement value within the refinement information onto mean value of values of neighboring samples associated with the second partition.
15. The decoder according to claim 14 , configured to, in applying the first and/or second refinement value, linearly combine the first and/or second refinement value with the mean value of values of the neighboring samples associated with the first partition, and/or the mean value of values of the neighboring samples associated with the second partition, respectively.
16. The decoder according to claim 14 , wherein the sample array is a depth map, and the decoder is configured to, in applying the first and/or second refinement value, scale the first and/or second refinement value using a quantization step size depending on a reference quantization step size at which a predetermined spatially sampled component associated with the sample array is transmitted, and use the reference quantization step size in order to reconstruct a texture sample array from the bitstream, with which the depth map is associated.
17. An encoder for encoding a predetermined block of a depth/disparity map associated with a texture picture into a data stream, configured to:
determine a texture threshold based on sample values of a reference block of the texture picture wherein the reference block is co-located to the predetermined block;
segment the reference block of the texture picture by thresholding the texture picture within the reference block using the texture threshold to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transfer the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
encode the predetermined block in units of the first and second partitions.
18. An encoder for encoding a predetermined block of a depth/disparity map associated with a texture picture into a data stream, configured to:
determine a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segment the reference block of the texture picture depending on a texture feature of the texture picture within the reference block using edge detection or by thresholding the texture picture using the texture threshold so as to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transfer the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
encode the predetermined block in units of the first and second partitions,
wherein the encoder is configured such that the segmentation, spatial transfer and encoding form one of a first set of coding options of the encoder, which is not part of a second set of coding options of the encoder, wherein the encoder is further configured to determine a dispersion of values of samples within the reference block of the texture picture; and
encode a coding option identifier into the data stream, use the coding option identifier as an index into the first set of coding options in case of the dispersion exceeding a predetermined threshold, with performing the segmentation, spatial transfer and encoding onto the predetermined block if the index points to the one coding option, and as an index into the second set of coding options in case of the dispersion succeeding the predetermined threshold.
19. A method for reconstructing a predetermined block of a depth/disparity map associated with a texture picture from a data stream, comprising:
determining a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segmenting the reference block of the texture picture by thresholding the texture picture within the reference block using the texture threshold to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transferring the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
decoding the predetermined block in units of the first and second partitions.
20. A method for reconstructing a predetermined block of a depth/disparity map associated with a texture picture from a data stream, comprising:
determining a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segmenting the reference block of the texture picture depending on a texture feature of the texture picture within the reference block using edge detection or by thresholding the texture picture using the texture threshold so as to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transferring the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
decoding the predetermined block in units of the first and second partitions,
wherein the method is performed such that the segmentation, spatial transfer and decoding form one of a first set of coding options, which is not part of a second set of coding options of the method, wherein the method further comprises
determining a dispersion of values of samples within the reference block of the texture picture; and
retrieving a coding option identifier from the data stream, using the coding option identifier as an index into the first set of coding options in case of the dispersion exceeding a predetermined threshold, with performing the segmentation, spatial transfer and decoding onto the predetermined block if the index points to the one coding option, and as an index into the second set of coding options in case of the dispersion succeeding the predetermined threshold.
21. A method for encoding a predetermined block of a depth/disparity map associated with a texture picture into a data stream, comprising:
determining a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segmenting the reference block of the texture picture by thresholding the texture picture within the reference block using the texture threshold to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transferring the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
encoding the predetermined block in units of the first and second partitions.
22. A method for encoding a predetermined block of a depth/disparity map associated with a texture picture into a data stream, comprising:
determining a texture threshold based on sample values of a reference block of the texture picture, wherein the reference block is co-located to the predetermined block;
segmenting the reference block of the texture picture depending on a texture feature of the texture picture within the reference block using edge detection or by thresholding the texture picture using the texture threshold so as to acquire a bi-segmentation of the reference block into first and second partitions;
spatially transferring the bi-segmentation of the reference block of the texture picture onto the predetermined block of the depth/disparity map so as to acquire first and second partitions of the predetermined block; and
encoding the predetermined block in units of the first and second partitions,
wherein the method is performed such that the segmentation, spatial transfer and encoding form one of a first set of coding options of the method, which is not part of a second set of coding options of the method, wherein the method further comprises
determining a dispersion of values of samples within the reference block of the texture picture; and
encoding a coding option identifier into the data stream, using the coding option identifier as an index into the first set of coding options in case of the dispersion exceeding a predetermined threshold, with performing the segmentation, spatial transfer and encoding onto the predetermined block if the index points to the one coding option, and as an index into the second set of coding options in case of the dispersion succeeding the predetermined threshold.
23. A non-transitory computer readable medium including a computer program comprising a program code for performing, when running on a computer, a method according to claim 19 .
24. A non-transitory computer readable medium including a computer program comprising a program code for performing, when running on a computer, a method according to claim 22 .