Method and apparatus for encoding/decoding images using a prediction method adopting in-loop filtering

• US 10,237,577 B2
• Filed: 07/15/2016
• Issued: 03/19/2019
• Est. Priority Date: 04/21/2011
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Intellectual Discovery Co., Ltd.
• Inventors: Jeong, Je Chang, Kim, Ki Baek, Jung, Dong Jin
• Primary Examiner(s): Elahi, Shan E
• Application Number:
  US15/210,978
• Publication Number:
  US 20160345025A1
• Time in Patent Office: 977 Days
• Field of Search: 37524013
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/45 performing compensation of the inverse transform mismatch, e.g. Inverse Discrete Cosine Transform [IDCT] mismatch
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

Disclosed is a prediction method adopting in-loop filtering. According to the present invention, a prediction method for encoding and decoding video comprises the following steps: generating a residual block of the current block through an inverse quantization and inverse transform; generating a prediction block of the current block through an intra-prediction; performing in-loop filtering on the current block in which the residual block and the prediction block are combined; and storing the current block, on which the in-loop filtering is performed, in a frame buffer for an intra-prediction of the next block to be encoded. As described above, prediction is performed using an in-loop filter during processes for encoding and decoding video, thereby improving the accuracy of prediction and reducing errors in prediction, thus improving the efficiency of video compression and reducing the amount of data to be transmitted.

Claims

1. A video decoding method performed by a video decoding apparatus, the method comprising:

obtaining quantized coefficients of a current block by decoding an input bitstream;

generating a residual block of the current block by performing an inverse-quantization and an inverse-transform on the quantized coefficients;

generating a prediction block by performing an intra prediction on the current block, the intra prediction being performed by using an intra prediction mode relating to the current block and neighboring pixels adjacent to the current block;

determining, based on a direction of the intra prediction mode, both whether to perform filtering on at least one predicted pixel adjacent to a boundary of the prediction block and a location of the at least one predicted pixel on which the filtering is performed;

performing the filtering on the at least one predicted pixel adjacent to the boundary of the prediction block when the filtering is determined to be performed based on the direction of the intra prediction mode; and

generating a restored block based on the residual block and the filtered prediction block.

2. The method of claim 1, wherein the boundary to which the at least one predicted pixel is adjacent is determined to be a top boundary, a bottom boundary, a left boundary or a right boundary of the prediction block in accordance with the intra prediction mode.

3. The method of claim 2, wherein the filtering is performed according to the intra prediction mode relating to the current block.

4. A video decoding apparatus, comprising:

a decoder configured to obtain quantized coefficients of a current block by decoding an input bitstream and generate a residual block of the current block by performing an inverse-quantization and an inverse-transform on the quantized coefficients;

a predictor configured to generate a prediction block by performing an intra prediction on the current block by using an intra prediction mode relating to the current block and neighboring pixels adjacent to the current block, determine, based on a direction of the intra prediction mode, both whether to perform filtering on at least one predicted pixel adjacent to a boundary of the prediction block and a location of the at least one predicted pixel on which the filtering is performed, and perform the filtering on the at least one predicted pixel adjacent to the boundary of the prediction block when the filtering is determined to be performed based on the direction of the intra prediction mode; and

an adder configured to generate a restored block based on the residual block and the filtered prediction block.

5. The apparatus of claim 4, wherein the boundary to which the at least one predicted pixel is adjacent is determined to be a top boundary, a bottom boundary, a left boundary or a right boundary of the prediction block in accordance with the intra prediction mode.

6. The apparatus of claim 5, wherein the prediction unit performs the filtering according to the intra prediction mode relating to the current block.

7. A video encoding method performed by a video encoding apparatus, the method comprising:

generating a prediction block by performing an intra prediction on a current block, the intra prediction being performed by using an intra prediction mode relating to the current block and neighboring pixels adjacent to the current block;

determining, based on a direction of the intra prediction mode, both whether to perform filtering on at least one predicted pixel adjacent to a boundary of the prediction block and a location of the at least one predicted pixel on which the filtering is performed;

performing the filtering on the at least one predicted pixel adjacent to the boundary of the prediction block when the filtering is determined to be performed based on the direction of the intra prediction mode;

generating a residual block based on the current block and the filtered prediction block; and

encoding the residual block by performing transformation and quantization on coefficients of the residual block.

8. A non-transitory computer-readable recording medium storing a bitstream that is generated by a video encoding method performed by a video encoding apparatus, the method comprising:

generating a prediction block by performing an intra prediction on a current block, the intra prediction being performed by using an intra prediction mode relating to the current block and neighboring pixels adjacent to the current block;

determining, based on a direction of the intra prediction mode, both whether to perform filtering on at least one predicted pixel adjacent to a boundary of the prediction block and a location of the at least one predicted pixel on which the filtering is performed;

performing the filtering on the at least one predicted pixel adjacent to the boundary of the prediction block when the filtering is determined to be performed based on the direction of the intra prediction mode;

generating a residual block based on the current block and the filtered prediction block; and

encoding the residual block by performing transformation and quantization on coefficients of the residual block.