EFFECTIVE WEDGELET PARTITION CODING

1 . A decoder for reconstructing a sample array from a data stream, configured to

predict a position of a wedgelet separation line within a predetermined block of the sample array depending on a wedgelet separation line of a neighboring block of the predetermined block such that the wedgelet separation line at the predicted position forms an extension of the wedgelet separation line of the neighboring block into the predetermined block,

refine the predicted position of the wedgelet separation line using refinement information signaled within the data stream, the wedgelet separation line of the predetermined block dividing the predetermined block into first and second wedgelet partitions, and

decode the predetermined block in units of the first and second wedgelet partition.

2 . The decoder according to claim 1 wherein the wedgelet separation line of the predetermined block is a straight line, the neighboring block is spatially adjacent to the predetermined block within the sample array, and the decoder is configured such that the wedgelet separation line at the predicted position forms a spatial co-linear extension of the wedgelet separation line of the neighboring block.

3 . The decoder according to claim 1 , configured such that the refinement is restricted such that a start position of the wedgelet separation line of the predetermined block, adjoining the neighboring block is maintained relative to the predicted position.

4 . The decoder according to claim 1 , configured to

retrieve a coding option identifier from the data stream,

if the coding option identifier comprises a predetermined value, check as to whether any of a set of candidate blocks neighboring the predetermined block comprises a wedgelet separation line continuing into the predetermined block, and

if so, perform the prediction of the position of the wedgelet separation line within the predetermined block, the refinement of the predicted position and the prediction of the predetermined block using the respective candidate block as the neighboring block, and

if not, predict the position of the wedgelet separation line within the predetermined block by setting an extension direction of the wedgelet separation line within the predetermined block depending on reconstructed neighboring samples neighboring the predetermined block or an intra-prediction direction of one or more intra-predicted blocks of the candidate blocks.

5 . The decoder according to claim 2 , configured to

retrieve a coding option identifier from the data stream,

if the coding option identifier comprises a predetermined value, check as to whether any of a set of candidate blocks neighboring the predetermined block comprises a wedgelet separation line continuing into the predetermined block, and

if so, perform the prediction of the position of the wedgelet separation line within the predetermined block, the refinement of the predicted position and the prediction of the predetermined block using the respective candidate block as the neighboring block, and

if not, predict the position of the wedgelet separation line within the predetermined block by setting an extension direction of the wedgelet separation line within the predetermined block depending on reconstructed neighboring samples neighboring the predetermined block or an intra-prediction direction of one or more intra-predicted blocks of the candidate blocks.

6 . The decoder according to claim 1 , wherein the decoder is configured to extract the refinement information from the data stream using entropy decoding different possible offsets from a direct extension sample position along the circumference of the predetermined block, which the wedgelet separation line of the neighboring block points to, measured in units of a sample position pitch have a probability estimate associated therewith which monotonically increases from greater offsets to smaller offsets.

7 . 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 wedgelet partition and a second constant partition value to samples of the sample array positioned within the second wedgelet partition.

8 . The decoder according to claim 7 , 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 wedgelet partitions so that each neighboring sample adjoins the wedgelet 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.

9 . The decoder according to claim 7 , configured to

refine the prediction of the predetermined block by applying a first refinement value within the refinement information onto the mean value of values of the neighboring samples associated with the first partition, and/or applying a second refinement value within the refinement information onto the mean value of values of the neighboring samples associated with the second partition.

10 . The decoder according to claim 9 , 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.

11 . The decoder according to claim 9 , configured to, in applying the first and/or second refinement value, retrieve the first and/or second refinement value from the data stream and scale the first and/or second refinement value as retrieved 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 within the data stream.

12 . The decoder according to claim 11 , wherein the sample array is a depth map, and the decoder is configured to use the reference quantization step size in order to reconstruct a texture sample array from the bitstream, with which the depth map is associated.

13 . The decoder according to claim 1 , wherein the sample array is a depth/disparity map associated with a picture, wherein the decoder is configured to

retrieve a coding option identifier from the data stream,

if the coding option identifier comprises a first predetermined value, perform the prediction of the position of the wedgelet separation line within the predetermined block, the refinement of the predicted position and the prediction of the predetermined block, and

if the coding option identifier comprises a second value,

segment a reference block of the picture, co-located to the predetermined block, by thresholding the picture within the reference block to achieve a bi-segmentation of the reference block into first and second partitions,

spatially transfer the bi-segmentation of the reference block of the 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.

14 . The decoder according to claim 1 , further configured to use the predetermined block as a reference in a prediction loop of the decoder.

15 . An encoder for encoding a sample array into a data stream, configured to

predict a position of a wedgelet separation line within a predetermined block of the sample array depending on a wedgelet separation line of a neighboring block of the predetermined block such that the wedgelet separation line at the predicted position forms an extension of the wedgelet separation line of the neighboring block into the predetermined block,

refine the predicted position of the wedgelet separation line using refinement information, the wedgelet separation line of the predetermined block dividing the predetermined block into first and second wedgelet partitions,

insert the refinement information into the data stream, and

encode the predetermined block in units of the first and second wedgelet partitions.

16 . The encoder according to claim 15 , further configured to use the predetermined block as a reference in motion and/or disparity compensated prediction.

17 . A method for reconstructing a sample array from a data stream, comprising

predicting a position of a wedgelet separation line within a predetermined block of the sample array depending on a wedgelet separation line of a neighboring block of the predetermined block such that the wedgelet separation line at the predicted position forms an extension of the wedgelet separation line of the neighboring block into the predetermined block,

refining the predicted position of the wedgelet separation line using refinement information signaled within the data stream, the wedgelet separation line of the predetermined block dividing the predetermined block into first and second wedgelet partitions, and

decoding the predetermined block in units of the first and second wedgelet partition.

18 . A method for encoding a sample array into a data stream, comprising

predicting a position of a wedgelet separation line within a predetermined block of the sample array depending on a wedgelet separation line of a neighboring block of the predetermined block such that the wedgelet separation line at the predicted position forms an extension of the wedgelet separation line of the neighboring block into the predetermined block,

refining the predicted position of the wedgelet separation line using refinement information, the wedgelet separation line of the predetermined block dividing the predetermined block into first and second wedgelet partitions,

inserting the refinement information into the data stream, and

encoding the predetermined block in units of the first and second wedgelet partitions

19 . 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

20 . 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 18 .