Simplification of mode dependent intra smoothing

Patent metadata

Field	Value
Publication number	US-9807385-B2
Application number	US-201313744827-A
Country	US
Kind code	B2
Filing date	Jan 18, 2013
Priority date	Jan 19, 2012
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

An apparatus comprising a processor configured to determine whether to apply an intra smoothing filter for a prediction unit (PU) based on a lookup table (LUT), wherein the LUT comprises data indicating the intra smoothing filter should not be applied for any PU with a block size of 8×8 pixels and associated with directional prediction mode. The disclosure also includes a method comprising generating reference samples, determining a size of a PU block, and selecting the reference samples based on PU block size, wherein filtered reference samples are not selected for PU blocks with a size of 8×8 pixels and associated with directional prediction mode.

First claim

What is claimed is:

1. A method of intra-frame prediction comprising:
generating a respective filtered reference sample for each of a plurality of prediction unit (PU) blocks by applying a smoothing filter to the PU block;
obtaining filtering switch data for each of the PU blocks from a Mode Dependent Intra Smoothing lookup table (MDIS LUT) based on a size and a prediction mode of the PU block, wherein the filtering switch data for PU blocks of size 8×8 and planar prediction mode indicates that an unfiltered reference sample should be used;
selecting, for each of the PU blocks, one of the filtered reference sample for the PU block or an unfiltered reference sample for the PU block based on the filtering switch data for the PU block; and
performing intra-frame prediction based on the selected samples, wherein a Bjontegaard Distortion rate that results from performing the prediction is approximately 0.00% change on luma (Y), approximately 0.02% gain on blue-difference chroma (Cb), approximately 0.01% gain on red-difference chroma (Cr) for the high efficiency case and approximately 0.05% loss on luma (Y), approximately 0.03% gain on blue-difference chroma (Cb), and approximately 0.02% loss on red-difference chroma (Cr) for the low complexity case.

2. The method of claim 1 , wherein the reference samples are generated and selected as part of a video encoding process.

3. The method of claim 1 , wherein the reference samples are generated and selected as part of a video decoding process.

4. The method of claim 1 , wherein the reference samples are generated and selected as part of a High Efficiency Video Coding (HEVC) Mode Dependent Intra Smoothing (MDIS) process.

5. The method of claim 1 , wherein the MDIS LUT comprises thirty six columns, wherein column 0 comprises data associated with planar mode, wherein column 1 comprises data associated with Intra DC mode, wherein columns 2-34 comprise data associated with directional intra mode, and wherein column 35 comprises data associated with intra LM mode.

6. The method of claim 5 , wherein the MDIS LUT further comprises:
a plurality of rows associated with PU block sizes; and
a plurality of cells associating the rows to the columns,
wherein each cell comprises a value of one to indicate that an intra smoothing filter should be applied to a PU block size or a value of zero to indicate that an intra smoothing filter should not be applied to a PU block size, and
wherein the MDIS LUT is expressed as:

0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

4 × 4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

8 × 8
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

16 × 16
1
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0

32 × 32
1
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

64 × 64
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

24
25
26
27
28
29
30
31
32
33
34
35

4 × 4
0
0
0
0
0
0
0
0
0
0
0
0

8 × 8
0
0
0
0
0
0
0
0
0
0
0
0

Assignees

• Futurewei Technologies Inc
• Univ Santa Clara

Inventors

• Li Guichun
• Liu Lingzhi
• Ling Nam
• Zheng Jianhua
• Zhang Chen-Xiong
• Song Li

Classifications

• H04N19/50

  using predictive coding (H04N19/61 takes precedence) · CPC title

• H04N19/117

  Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) · CPC title

• H04N19/157

  Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter · CPC title

• H04N19/593

  involving spatial prediction techniques · CPC title

• H04N19/18 Primary

  the unit being a set of transform coefficients · CPC title