Reference pixel reduction for intra LM prediction

Patent metadata

Field	Value
Publication number	US-9307237-B2
Application number	US-201313745134-A
Country	US
Kind code	B2
Filing date	Jan 18, 2013
Priority date	Jan 19, 2012
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

A video codec comprising a processor configured to generate a prediction block for a chroma block, wherein the prediction block comprises a predicted chroma sample, wherein the predicted chroma sample is based on a filtered reconstructed luma sample located in a corresponding reconstructed luma block, a plurality of downsampled filtered reconstructed luma samples located in positions neighboring the corresponding reconstructed luma block, and a plurality of downsampled chroma samples located in positions neighboring the chroma block.

First claim

What is claimed is:

1. A video codec comprising:
a processor configured to:
generate a prediction block for a chroma block, wherein the prediction block comprises a predicted chroma sample, wherein the predicted chroma sample is based on:
a filtered reconstructed luma sample located in a corresponding reconstructed luma block;
a plurality of downsampled filtered reconstructed luma samples located in positions neighboring the corresponding reconstructed luma block, the downsampled filtered reconstructed luma samples comprise every Nth filtered reconstructed luma sample of a top neighboring vector of reconstructed luma samples and a left neighboring vector of reconstructed luma samples, where N is an integer greater than one; and
a plurality of downsampled chroma samples located in positions neighboring the chroma block, the downsampled chroma samples comprise every Nth chroma sample of a top neighboring vector of chroma samples and a left neighboring vector of chroma samples;

generate a second reconstructed luma block corresponding to a second chroma block; and
generate a second prediction block for the second chroma block based on the corresponding second reconstructed luma block, wherein the second prediction block is further based on a subset of a plurality of filtered reconstructed luma samples located in positions neighboring the second reconstructed luma block when the second chroma block is of dimension 16×16 or 8×8, wherein the subset is obtained by downsampling, and otherwise wherein the second prediction block is further based on the plurality of filtered reconstructed luma samples located in positions neighboring the second reconstructed luma block.

2. A video codec comprising:
a processor configured to:
generate a prediction block for a chroma block, wherein the prediction block comprises a predicted chroma sample, wherein the predicted chroma sample is based on:
a filtered reconstructed luma sample located in a corresponding reconstructed luma block;
a plurality of downsampled filtered reconstructed luma samples located in positions neighboring the corresponding reconstructed luma block, wherein the downsampled filtered reconstructed luma samples comprise a sliding average of a top neighboring vector of reconstructed luma samples and a left neighboring vector of reconstructed luma samples; and
a plurality of downsampled chroma samples located in positions neighboring the chroma block, the downsampled chroma samples comprise a sliding average of a top neighboring vector of chroma samples and a left neighboring vector of chroma samples;

wherein the sliding average of the top neighboring vector of reconstructed luma samples comprises

1
N

⁢

∑

i
=
0

N
-
1

⁢

p
Y
′

⁡

[

N
*
x

+
i

,

-
1

]

for x=0, . . . , nS/N−1, where nS is a dimension of the chroma block, N is a downsampling factor, and p Y ′[x, −1] for x=0, . . . , nS−1 is the left neighboring vector, and wherein the sliding average of the left neighboring vector of reconstructed luma samples comprise

1
N

⁢

∑

i
=
0

N
-
1

⁢

p
Y
′

⁡

[

-
1

,

N
*
y

+
i

]

for y=0, . . . , nS/N−1, where p Y ′[−1, y] for y=0, . . . , nS−1 is the top neighboring vector.

3. A method used in video coding to generate predicted chroma samples for a chroma block, comprising:
downsampling, performed by a video coder at least partially implemented in hardware, filtered reconstructed luma samples located in positions neighboring a reconstructed luma block to generate a plurality of downsampled filtered reconstructed luma samples, the downsampled filtered reconstructed luma samples comprise every Nth filtered reconstructed luma sample of a top neighboring vector of reconstructed luma samples and a left neighboring vector of reconstructed luma samples, where N is an integer greater than one;
downsampling, performed by the video coder, reconstructed chroma samples located in positions neighboring a chroma block to generate a plurality of downsampled reconstructed chroma samples, the downsampled chroma samples comprise every Nth chroma sample of a top neighboring vector of chroma samples and a left neighboring vector of chroma samples; and
generating, performed by the video coder, a prediction block for the chroma block, wherein the prediction block comprises a predicted chroma sample, wherein the predicted chroma sample is based on:
a filtered reconstructed luma sample located in the reconstructed luma block;
the plurality of downsampled filtered reconstructed luma samples; and
the plurality of downsampled reconstructed chroma samples; and

generating a second reconstructed luma block corresponding to a second chroma block; generating a second prediction block for the second chroma block based on the corresponding second reconstructed luma block, wherein the second prediction block is further based on a subset of a plurality of filtered reconstructed luma samples located in positions neighboring the second reconstructed luma block when the second chroma block is of dimension 16×16 or 8×8, wherein the subset is obtained by downsampling, and otherwise wherein the second prediction block is further based on the plurality of filtered reconstructed luma samples located in positions neighboring the second reconstructed luma block.

4. The method of claim 3 , wherein the downsampled filtered reconstructed luma samples comprise an average of a top neighboring vector of reconstructed luma samples and a left neighboring vector of reconstructed luma samples.

5. The method of claim 4 , wherein the downsampled chroma samples comprise a sliding average

Assignees

• Futurewei Technologies Inc
• Santa Clara University

Inventors

• Liu Lingzhi
• Li Guichun
• Ling Nam
• Zheng Jianhua
• Zhang Philipp
• Song Li

Classifications

• H04N19/503 Primary

  involving temporal prediction (adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109) · CPC title

• H04N19/50 Primary

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

• H04N19/186

  the unit being a colour or a chrominance component · CPC title

• H04N19/00569 Primary

  Electricity · mapped topic