US-12627842-B2 - Image coding method and device using deblocking filtering

US12627842B2US 12627842 B2US12627842 B2US 12627842B2US-12627842-B2

Abstract

A method by which a decoding device decodes an image, according to the present document, comprises the steps of: generating a restoration picture on the basis of prediction samples of a coding block; deriving a boundary strength (BS) for a boundary of the coding block in the restoration picture; performing deblocking filtering on the boundary of the coding block on the basis of the boundary strength; and deriving a modified restoration picture for the restoration picture on the basis of the deblocking filtering, wherein the boundary strength is derived on the basis of a prediction mode of a first block and a second block that are adjacent to the boundary of the coding block, and the prediction mode of the first block or the second block is derived on the basis of whether the prediction mode of the first block or the second block is a current picture referencing (CPR) mode to be coded in reference to a current picture.

Inventors

Hyeongmoon JANG
Junghak NAM

Assignees

LG ELECTRONICS INC.

Dates

Publication Date: 20260512
Application Date: 20240815

Claims (4)

1 . An image decoding method performed by a decoding apparatus, the method comprising: generating a reconstructed picture based on predicted samples of a first block; deriving a boundary strength (bs) for a boundary of the first block in the reconstructed picture; performing a deblocking filtering on the boundary of the first block based on the boundary strength; and deriving a modified reconstructed picture for the reconstructed picture based on the deblocking filtering, wherein the boundary strength is derived based on prediction modes of the first block and a second block adjacent to the boundary of the first block, wherein based on a prediction mode of the first block being a current picture referencing (CPR) mode which is coded with reference to a current picture and a prediction mode of the second block being palette mode, a value of the boundary strength is set equal to 1, wherein based on the boundary of the first block being a vertical boundary, the first block is located on a left side of the vertical boundary and the second block is located on a right side of the vertical boundary, and wherein based on the boundary of the first block being a horizontal boundary, the first block is located on an upper side of the horizontal boundary, and the second block is located on a lower side of the horizontal boundary.
2 . An image encoding method performed by an encoding apparatus, the method comprising: generating a reconstructed picture based on predicted samples of a first block; deriving a boundary strength (bs) for a boundary of the first block in the reconstructed picture; performing a deblocking filtering on the boundary of the first block based on the boundary strength; deriving a modified reconstructed picture for the reconstructed picture based on the deblocking filtering; and encoding image information comprising information on the first block, wherein the boundary strength is derived based on prediction modes of the first block and a second block adjacent to the boundary of the first block, wherein based on a prediction mode of the first block being a current picture referencing (CPR) mode which is coded with reference to a current picture and a prediction mode of the second block being palette mode, a value of the boundary strength is set equal to 1, wherein based on the boundary of the first block being a vertical boundary, the first block is located on a left side of the vertical boundary and the second block is located on a right side of the vertical boundary, and wherein based on the boundary of the first block being a horizontal boundary, the first block is located on an upper side of the horizontal boundary, and the second block is located on a lower side of the horizontal boundary.
3 . A non-transitory computer-readable storage medium storing encoded image information generated by the image encoding method of claim 2 .
4 . A transmission method of data for an image, the method comprising: obtaining a bitstream for image information, wherein the bitstream is generated based on generating a reconstructed picture based on predicted samples of a first block, deriving a boundary strength (bs) for a boundary of the first block in the reconstructed picture, performing a deblocking filtering on the boundary of the first block based on the boundary strength, deriving a modified reconstructed picture for the reconstructed picture based on the deblocking filtering, and encoding image information comprising information on the first block; and transmitting the data comprising the bitstream, wherein the boundary strength is derived based on prediction modes of the first block and a second block adjacent to the boundary of the first block, wherein based on a prediction mode of the first block being a current picture referencing (CPR) mode which is coded with reference to a current picture and a prediction mode of the second block being palette mode, a value of the boundary strength is set equal to 1, wherein based on the boundary of the first block being a vertical boundary, the first block is located on a left side of the vertical boundary and the second block is located on a right side of the vertical boundary, and wherein based on the boundary of the first block being a horizontal boundary, the first block is located on an upper side of the horizontal boundary, and the second block is located on a lower side of the horizontal boundary.

Description

CROSS-REFERENCE TO PRIOR APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/219,012, filed Jul. 6, 2023, which is a continuation of U.S. patent application Ser. No. 17/688,533, filed Mar. 7, 2022, which is continuation of U.S. patent application Ser. No. 17/356,016, filed Jun. 23, 2021, which is a Bypass Continuation of International Application No. PCT/KR2020/000025, filed Jan. 2, 2020 (published Jul. 9, 2020 as WO 2020/141885 A1), which claims priority to and the benefit of U.S. Provisional Application No. 62/787,743, filed Jan. 2, 2019, each hereby expressly incorporated by reference in its entirety. BACKGROUND OF THE DISCLOSURE Field of the Disclosure The present document relates to an image coding technology, and more specifically, to an image coding method and apparatus using a deblocking filter process. Related Art The demands for high-resolution and high-quality images and video, such as an ultra high definition (UHD) image and video of 4K or 8K or more, are recently increasing in various fields. As image and video data become high resolution and high quality, the amount of information or the number of bits that is relatively transmitted is increased compared to the existing image and video data. Accordingly, if image data is transmitted using a medium, such as the existing wired or wireless wideband line, or image and video data are stored using the existing storage medium, transmission costs and storage costs are increased. Furthermore, interests and demands for immersive media, such as virtual reality (VR), artificial reality (AR) content or a hologram, are recently increasing. The broadcasting of an image and video having image characteristics different from those of real images, such as game images, is increasing. Accordingly, there is a need for a high-efficiency image and video compression technology in order to effectively compress and transmit or store and playback information of high-resolution and high-quality images and video having such various characteristics. SUMMARY An object of the present document is to provide a method and an apparatus for enhancing image coding efficiency. Another object of the present document is to provide a method and an apparatus for improving an image quality of an image. Still another object of the present document is to provide a method and an apparatus for designing a boundary strength in consideration of the characteristics of a block in a process of performing a deblocking filter process. An exemplary embodiment of the present document provides an image decoding method performed by a decoding apparatus. The method includes generating a reconstructed picture based on predicted samples of a coding block, deriving a boundary strength (bs) for a boundary of the coding block in the reconstructed picture, performing a deblocking filtering on the boundary of the coding block based on the boundary strength, and deriving a modified reconstructed picture for the reconstructed picture based on the deblocking filtering, in which the boundary strength is derived based on prediction modes of a first block and a second block adjacent to the boundary of the coding block, and derived based on whether the prediction mode of the first block or the prediction mode of the second block is a current picture referencing (CPR) mode coded with reference to a current picture. Another exemplary embodiment of the present document provides an image encoding method performed by an encoding apparatus. The method includes generating a reconstructed picture based on predicted samples of a coding block, deriving a boundary strength (bs) for a boundary of the coding block in the reconstructed picture, performing a deblocking filtering on the boundary of the coding block based on the boundary strength, deriving a modified reconstructed picture for the reconstructed picture based on the deblocking filtering, and encoding image information including information on the coding block, in which the boundary strength is derived based on prediction modes of a first block and a second block adjacent to the boundary of the coding block, and derived based on whether the prediction mode of the first block or the prediction mode of the second block is a current picture referencing (CPR) mode coded with reference to a current picture. Still another exemplary embodiment of the present disclosure provides a digital storage medium for storing encoded image information causing an image decoding method to be performed, as a computer readable digital storage medium. The present document may enhance the overall image/video compression efficiency. The present document may improve the image quality of the image/the video. The present document may design the boundary strength in consideration of the characteristics of the block in the process of performing the deblocking filter process to efficiently remove the artifact of the boundary between the blocks, thereby improving the