# US 2019/0174143 A1 · Intra-prediction edge filtering

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- Number: US 2019/0174143 A1
- Document ID: US20190174143A1
- Status: Published application
- Kind: A1
- Application number: 16/267,552
- Filed: 2019-02-05
- Published: 2019-06-06
- Earliest claimed: 2017-05-09
- Assignees: Google Inc.
- Applicants: Google LLC
- Inventors: Joseph Young
- Web page: https://patentgrep.com/patent/US20190174143A1

## CPC

- H04N 19/593: involving spatial prediction techniques
- H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635)
- H04N 19/124: Quantisation
- H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
- H04N 19/182: the unit being a pixel
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/82: involving filtering within a prediction loop
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

Coding a current block using a directional intra prediction mode is disclosed. The intra prediction mode includes a prediction angle and uses pixels peripheral to the current block to generate a prediction block. An apparatus determines, using the prediction angle, a filter to apply to the pixels peripheral to the current block; filters, using the filter, at least some of the pixels peripheral to the current block resulting in modified pixels; and generates a prediction block for the current block using the intra prediction mode and the modified pixels.

## Claims

### Claim 1

An apparatus for encoding or decoding a current block using an intra prediction mode, the intra prediction mode comprising a prediction angle and using pixels peripheral to the current block, the apparatus:
determines, using the prediction angle, a filter to apply to the pixels peripheral to the current block;
filters, using the filter, at least some of the pixels peripheral to the current block resulting in modified pixels; and
generates a prediction block for the current block using the intra prediction mode and the modified pixels.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the pixels peripheral to the current block comprise first pixels in a row above the current block and second pixels in a column left of the current block, and wherein to determine the filter further comprises to:
determine, using the prediction angle and a vertical line parallel to the column, a first filter for the first pixels and a second filter for the second pixels.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein determining the first filter and the second filter is further based on a size of the current block.

### Claim 4 (depends on 2)

The apparatus of claim 2, wherein determining the first filter and the second filter is further based on a quantization parameter of the current block.

### Claim 5 (depends on 2)

The apparatus of claim 2, wherein
to determine the filter comprises to determine a filter strength, and
to filter at least some of the pixels peripheral to the current block further comprises to:
apply the filter one or more times based on the filter strength.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the filter is an n-tap filter.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the apparatus further:
decodes, from an encoded bitstream, an indicator to apply the filter to the pixels peripheral to the current block.

### Claim 8

A method for encoding or decoding a current block using an intra prediction mode, the intra prediction mode comprising a prediction angle and using pixels peripheral to the current block, the method comprising:
selecting, based on the prediction angle, a filter to apply to at least some of the pixels peripheral to the current block;
filtering, using the filter, the at least some of the pixels peripheral to the current block resulting in modified pixels; and
generating a prediction block for the current block using the intra prediction mode and the modified pixels.

### Claim 9 (depends on 8)

The method of claim 8, wherein the filter is further selected based a size of the current block.

### Claim 10 (depends on 9)

The method of claim 9, wherein selecting, based on the prediction angle, the filter to apply to the at least some of the pixels peripheral to the current block comprises:
selecting a bypass filter when the prediction angle is below an angle threshold value and a size of the current block is below a threshold size value.

### Claim 11 (depends on 9)

The method of claim 9, wherein selecting, based on the prediction angle, the filter to apply to the at least some of the pixels peripheral to the current block comprising:
on condition that the current block is of size 4×4, selecting a bypass filter as the filter.

### Claim 12 (depends on 8)

The method of claim 8, wherein the filter is selected from a set of filters comprising three filters.

### Claim 13 (depends on 8)

The method of claim 8, wherein the filter comprises weight values 5, 6, and 5.

### Claim 14 (depends on 8)

The method of claim 8, wherein selecting, based on the prediction angle, the filter to apply to the at least some of the pixels peripheral to the current block comprising:
determining a filter strength based on the prediction angle; and
selecting the filter based on the filter strength.

### Claim 15

An apparatus for encoding or decoding a current block using an intra prediction mode, the intra prediction mode comprising a prediction angle and using pixels peripheral to the current block, the apparatus comprising:
a memory; and
a processor, the processor configured to execute instructions stored in the memory to:
select, based on a size of the current block, a filter to apply to at least some of the pixels peripheral to the current block;
filter, using the filter, the at least some of the pixels peripheral to the current block resulting in modified pixels; and
generate a prediction block for the current block using the intra prediction mode and the modified pixels.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the filter is further selected based on the prediction angle.

### Claim 17 (depends on 16)

The apparatus of claim 16, wherein to select, based on the size of the current block, the filter to apply to the at least some of the pixels peripheral to the current block comprises to:
select a bypass filter when the prediction angle is below an angle threshold value and the size of the current block is below a threshold size value.

### Claim 18 (depends on 16)

The apparatus of claim 16, wherein selecting, based on the size of the current block, the filter to apply to the at least some of the pixels peripheral to the current block comprising:
on condition that the current block is of size 4×4, selecting a bypass filter as the filter.

### Claim 19 (depends on 15)

The apparatus of claim 15, wherein the filter is selected from a set of filters comprising three filters.

### Claim 20 (depends on 15)

The apparatus of claim 15, wherein the filter comprises weight values 5, 6, and 5.