Reference pixel selection and filtering for intra coding of depth map

1. A video codec configured to:

obtain a current block and a plurality of neighboring pixels, wherein the current block comprises a first partition and a second partition, wherein the first partition comprises at least top-right, top-left, and bottom-left corner pixels of the current block, wherein the second partition comprises at least one pixel in a top row of the current block, and wherein one of two pixels, located at the middle of a bottom row of an upper neighboring block with respect to the current block, is selected as a reference pixel;

select one or more reference pixels from the plurality of neighboring pixels; and

predict a plurality of pixels located in the second partition based on the reference pixels.

2. The video codec of claim 1 , further configured to determine whether to filter the reference pixels before predicting the pixels in the second partition, wherein the determination is based on at least one of an intra prediction mode of the current block and a size of the current block.

3. The video codec of claim 2 , further configured to generate a filtered reference pixel by filtering the reference pixels when the size of the current block falls within a predefined range, wherein the filtered reference pixel is generated as a linear combination of a plurality of reference pixels across multiple rows or multiple columns, and wherein the plurality of pixels in the second partition are predicted using the filtered reference pixel.

4. The video codec of claim 2 , further configured to generate a filtered reference pixel by filtering the reference pixels when an index of the intra prediction mode falls within a predefined range, wherein the filtered reference pixel is generated as a linear combination of a plurality of reference pixels, and wherein the plurality of pixels in the second partition are predicted using the filtered reference pixel.

5. The video codec of claim 2 , further configured to insert a binary flag into a bitstream comprising encoded information of the current block, wherein the binary flag specifies whether the current block is filtered before intra prediction, and wherein the binary flag determines whether a corresponding decoder receiving the bitstream applies filtering during decoding of the current block.

6. An apparatus, used in video coding, comprising:

a processor configured to:

obtain a current block comprising a first partition and a second partition, wherein the first partition comprises at least top-right, top-left, and bottom-left corner samples of the current block;

select a reference sample from an upper-right neighboring block of the current block and a lower-left neighboring block of the current block, wherein the reference sample is either a first sample located at a bottom-right corner of the lower-left neighboring block or a second sample located at a bottom-right corner of the upper-right neighboring block; and

predict samples located in the second partition using the reference sample selected from the upper-right neighboring block and the lower-left neighboring block

wherein the current block has a left neighboring block and an upper neighboring block, wherein a third sample is located at the top-right corner of the left neighboring block, wherein a fourth sample is located at the bottom-left corner of the upper neighboring block, and wherein selecting the reference sample comprises: computing a first absolute difference between the first sample and the third sample; and computing a second absolute difference between the second sample and the fourth sample.

7. The apparatus of claim 6 , wherein the first absolute difference is greater than the second absolute difference, and wherein the first sample is selected as the reference sample because the first absolute difference is greater than the second absolute difference.

8. The apparatus of claim 6 , wherein the first absolute difference is equal to or less than the second absolute difference, and wherein the second sample is selected as the reference sample because the first absolute difference is equal to or less than the second absolute difference.

9. A method of intra prediction in Three-Dimensional-High Efficiency Video Coding (3D-HEVC), the method comprising:

obtaining a plurality of neighboring samples with respect to a current block, wherein the plurality of neighboring samples comprise a first sample located at a bottom-right corner of a lower-left neighboring block and a second sample located at a bottom-right corner of an upper-right neighboring block, wherein the plurality of neighboring samples are denoted as p[x][y], with x=−1, y=−1 . . . nTbS*2−1 and with x=0 . . . nTbS*2−1, y=−1, wherein nTbS specifies a size of the current block, wherein the first and second samples are represented by p[−1][nTbS*2−1] and p[nTbS*2−1][−1], respectively;

receiving a partition pattern that specifies a partitioning of the current block into partition 0 and partition 1, wherein the partition 0 comprises at least top-right, top-left, and bottom-left corner samples of the current block; and

selecting one of the first sample and the second sample as a reference sample for intra predicting the partition 1, wherein the selection of the reference sample is based on a first absolute difference between samples p[−1][0] and p[−1][nTbS*2−1] and a second absolute difference between samples p[0][−1] and p[nTbS*2−1][−1].

10. The method of claim 9 , wherein the first and second absolute differences are denoted as vertAbsDiff and horAbsDiff, respectively, and wherein the reference sample is used as a direct current (DC) mean value, denoted as dcValBR, calculated using operation:

dcValBR =( horAbsDiff>vertAbsDiff )? p[nTbS* 2−1][−1]: p[ −1][ nTbS* 2−1]).  (8)

11. The method of claim 10 , wherein vertAbsDiff and horAbsDiff are calculated using operations:

vertAbsDiff=Abs ( p[− 1][0]− p[− 1][ nTbS* 2−1]); and

horAbsDiff=Abs ( p[ 0][−1]− p[nTbS* 2−1][−1]).

12. The method of claim 10 , wherein the partition pattern is a binary array comprising pattern values denoted as partitionPattern[x][y] with x, y=0 . . . nTbS−1, wherein the top-right, top-left, and bottom-left corner samples of the partition 0 are indicated by two binary variables, vertEdgeFlag and horEdgeFlag, both being equal to 0, and wherein vertEdgeFlag and horEdgeFlag are derived using the following operations:

vert EdgeFlag=(partitionPattern[0][0]!=partitionPattern[ nTbS− 1][0]), and

hor EdgeFlag=(partitionPattern[0][0]!=partitionPattern[0][ nTbS− 1]).

13. The method of claim 10 , further comprising intra predicting the partition 0 using a second DC mean value, denoted as dcValLT, calculated using operation:

dcValLT =( p[− 1][0]+ p[ 0][−1])>>1,

wherein, for x, y=0 . . . nTbS−1, intermediate variables predDcVal and dcOffset are defined and derived using the following operations:

predDcVal =(partitionPattern[ x][y ==partitionPattern[0][0)? dcValLT:dcValBR, and

dc Offset= Dc Offset[ xTb][yTb ][partitionPattern[ x][y]],

wherein (xTb, yTb) specifies a top-left sample location of the current block relative to a top-left sample of a depth map that comprises the current block, and wherein predicted sample values of the current block, denoted as predSamples[x][y] with x, y=0 . . . nTbS−1, are derived based on predDcVal and dcOffset.

14. A video codec configured to:

obtain a current block and a plurality of neighboring pixels, wherein the current block comprises a first partition and a second partition, wherein the first partition comprises at least top-right, top-left, and bottom-left corner pixels of the current block, wherein the second partition comprises at least one pixel in a leftmost column of the current block, and wherein one of two pixels, located at the middle of a rightmost column of a left neighboring block with respect to the current block, is selected as a reference pixel;

select one or more reference pixels from the plurality of neighboring pixels; and

predict a plurality of pixels located in the second partition based on the reference pixels.