US-12621431-B2 - Method and apparatus for encoding/decoding image

US12621431B2US 12621431 B2US12621431 B2US 12621431B2US-12621431-B2

Abstract

The objective of the present invention is to provide a method and an apparatus for intra-prediction. In addition, the objective of the present invention is to provide a method and an apparatus for intra-prediction on a subblock unit basis. Furthermore, the objective of the present invention is to provide a method and an apparatus for determining a division and an encoding order of subblock units.

Inventors

Ki Baek Kim

Assignees

B1 INSTITUTE OF IMAGE TECHNOLOGY, INC.

Dates

Publication Date: 20260505
Application Date: 20250829
Priority Date: 20180401

Claims (5)

1 . An image decoding method performed by an image decoding apparatus, the method comprising: generating a prediction block of a coding block by performing intra prediction; and reconstructing the coding block based on the prediction block, wherein the reconstructing the coding block further comprises: obtaining a quantized transform coefficient for the coding block; obtaining a transform coefficient for the coding block based on the quantized transform coefficient; and generating a residual block of the coding block based on the transform coefficient, wherein the coding block is reconstructed further based on the residual block, wherein the transform coefficient is obtained by inverse-quantizing the quantized transform coefficient, wherein the residual block is generated by inverse-transforming the transform coefficient, wherein the coding block is generated by adding the prediction block and the residual block, wherein the performing intra prediction comprises interpolating reference samples, wherein one among fixed filtering or adaptive filtering is selectively performed according to an intra prediction mode for the coding block for the interpolating reference samples, and wherein the fixed filtering uses one interpolation filter pre-defined in the image decoding apparatus, and the adaptive filtering selectively uses one among a plurality of interpolation filters pre-defined in the image decoding apparatus.
2 . The method of claim 1 , wherein the plurality of interpolation filters comprises at least one of a 4-tap cubic filter or a 4-tap gaussian filter.
3 . An image encoding method performed by an image encoding apparatus, the method comprising: generating a prediction block of a coding block by performing intra prediction; and encoding the coding block based on the prediction block, wherein the encoding the coding block further comprises: generating a residual block of the coding block based on the prediction block; generating a transform coefficient for the coding block based on the residual block; generating a quantized transform coefficient for the coding block based on the transform coefficient; and encoding the coding block based on the quantized transform coefficient, wherein the residual block is generated by subtracting the prediction block from the coding block, wherein the transform coefficient is generated by transforming the residual block, wherein the quantized transform coefficient is generated by quantizing the transform coefficient, wherein the performing intra prediction comprises interpolating reference samples, wherein one among fixed filtering or adaptive filtering is selectively performed according to an intra prediction mode for the coding block for the interpolating reference samples, and wherein the fixed filtering uses one interpolation filter pre-defined in the image encoding apparatus, and the adaptive filtering selectively uses one among a plurality of interpolation filters pre-defined in the image encoding apparatus.
4 . The method of claim 3 , wherein the plurality of interpolation filters comprises at least one of a 4-tap cubic filter or a 4-tap gaussian filter.
5 . A method of transmitting a bitstream generated by an image encoding method performed by an image encoding apparatus, the method comprising: generating a prediction block of a coding block by performing intra prediction; encoding the coding block based on the prediction block into the bitstream; and transmitting the bitstream to an image decoding apparatus, wherein the encoding the coding block further comprises: generating a residual block of the coding block based on the prediction block; generating a transform coefficient for the coding block based on the residual block; generating a quantized transform coefficient for the coding block based on the transform coefficient; and encoding the coding block based on the quantized transform coefficient, wherein the residual block is generated by subtracting the prediction block from the coding block, wherein the transform coefficient is generated by transforming the residual block, wherein the quantized transform coefficient is generated by quantizing the transform coefficient, wherein the performing intra prediction comprises interpolating reference samples, wherein one among fixed filtering or adaptive filtering is selectively performed according to an intra prediction mode for the coding block for the interpolating reference samples, and wherein the fixed filtering uses one interpolation filter pre-defined in the image encoding apparatus, and the adaptive filtering selectively uses one among a plurality of interpolation filters pre-defined in the image encoding apparatus.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of application Ser. No. 18/775,476, filed on Jul. 17, 2024, which is a continuation of application Ser. No. 17/680,674, filed on Feb. 25, 2022, which is now U.S. Pat. No., 12,075,026, which is a continuation of application Ser. No. 17/040,765 filed on Sep. 23, 2020, which is now U.S. Pat. No. 11,297,309, which claims the benefit of U.S. National Stage Application of International Application No. PCT/KR2019/003777, filed on Apr. 1, 2019, and published as WO 2019/194485 on Oct. 10, 2019. This application and PCT/KR2019/003777 claim the benefit under 35 USC 119(a) and 365(b) of Korean Patent Application No. 10-2018-0037812 filed on Apr. 1, 2018 in the Korean Intellectual Property Office. The disclosures of PCT/KR2019/003777 and Korean Patent Application No. 10-2018-0037812 are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a technique of encoding and decoding an image, and more particularly, to a method and apparatus for performing encoding/decoding in intra-prediction. BACKGROUND ART Along with the widespread use of the Internet and portable terminals and the development of information and communication technology, multimedia data is increasingly being used. Accordingly, in order to provide various services or perform various tasks through image prediction in various systems, there is a pressing need for improving the performance and efficiency of an image processing system. However, research and development achievements are yet to catch up with the trend. As such, an existing method and apparatus for encoding/decoding an image needs performance improvement in image processing, particularly in image encoding or image decoding. DISCLOSURE Technical Problem It is an object of the present disclosure to provide a method and apparatus for performing intra-prediction. It is another object of the present disclosure to provide a method and apparatus for performing subblock-wise intra-prediction. It is another object of the present disclosure to provide a method and apparatus for performing partitioning into subblocks and determining a coding order of the subblocks. Technical Solution In a method and apparatus for image encoding/decoding according to the present disclosure, a candidate group of partition types for a current block is configured, and a partition type of the current block into subblocks is determined based on the candidate group and a candidate index, an intra-prediction mode is derived in units of the current block, and the current block is intra-predicted based on the intra-prediction mode of the current block and the partition type. Advantageous Effects According to the present disclosure, encoding/decoding performance may be improved through subblock-wise intra-prediction. Further, according to the present disclosure, prediction accuracy may be increased by efficiently configuring a candidate group of subblock-wise partition types. Further, according to the present disclosure, intra-prediction encoding/decoding efficiency may be improved by adapting a subblock-wise coding order. DESCRIPTION OF DRAWINGS FIG. 1 is a conceptual diagram illustrating an image encoding and decoding system according to an embodiment of the present disclosure. FIG. 2 is a block diagram illustrating an image encoding apparatus according to an embodiment of the present disclosure. FIG. 3 is a block diagram illustrating an image decoding apparatus according to an embodiment of the present disclosure. FIG. 4 is an exemplary diagram illustrating various partition types which may be obtained in a block splitter of the present disclosure. FIG. 5 is an exemplary diagram illustrating intra-prediction modes according to an embodiment of the present disclosure. FIG. 6 is an exemplary diagram illustrating a configuration of reference pixels used for intra-prediction according to an embodiment of the present disclosure. FIG. 7 is a conceptual diagram illustrating a target block for intra-prediction and blocks neighboring to the target block according to an embodiment of the present disclosure. FIG. 8 is a diagram illustrating various subblock partition types which may be obtained from a coding block. FIG. 9 is an exemplary diagram illustrating reference pixel regions used for intra-prediction modes according to an embodiment of the present disclosure. FIG. 10 is an exemplary diagram illustrating coding orders available in diagonal up right prediction modes according to an embodiment of the present disclosure. FIG. 11 is an exemplary diagram illustrating coding orders available in horizontal modes according to an embodiment of the present disclosure. FIG. 12 is an exemplary diagram illustrating coding orders available in diagonal down right prediction modes according to an embodiment of the present disclosure. FIG. 13 is an exemplary diagram illustrating coding orders available in vertical modes according to an embodiment of the