US-12621483-B2 - Image decoding method for performing inter-prediction when prediction mode for current block ultimately cannot be selected, and device for same

US12621483B2US 12621483 B2US12621483 B2US 12621483B2US-12621483-B2

Abstract

The present disclosure relates to an image decoding and encoding method which can efficiently perform inter-prediction by applying a regular merge mode to the current block on the basis of the case in which an MMVD mode, a merge sub-block mode, a CIIP mode, and a partitioning mode, in which prediction is performed by dividing the current block into two partitions, are not available for the current block.

Inventors

Hyeongmoon JANG
Naeri PARK
Seunghwan Kim

Assignees

LG ELECTRONICS INC.

Dates

Publication Date: 20260505
Application Date: 20240823

Claims (3)

1 . An image decoding method performed by a decoding apparatus, the image decoding method comprising: receiving image information including inter prediction mode information through a bitstream; generating a merge candidate list of a current block based on the inter prediction mode information; deriving motion information of the current block based on a candidate selected from the merge candidate list; and generating prediction samples of the current block based on the motion information, wherein the image information includes a first enabled flag for a combined inter-picture merge and intra-picture prediction (CIIP) mode and a second enabled flag for a partitioning prediction mode, wherein for the partitioning prediction mode, prediction is performed by partitioning a block, wherein the partitioning includes triangle partitioning, wherein a merge data syntax is related to the inter prediction mode information, wherein the merge data syntax included in the image information includes at least one of a regular merge flag related to whether a regular merge mode is applied to the current block, an mmvd merge flag related to whether a merge mode with motion vector difference (MMVD) is applied to the current block and a merge subblock flag related to whether a subblock merge mode is applied to the current block, wherein a parsing order of the regular merge flag precedes a parsing order of the mmvd merge flag, and wherein, based on a value of the first enabled flag being equal to 0, a value of the second enabled flag being equal to 0, the regular merge flag, which indicates a value of 1, being not present, a value of the merge subblock flag being equal to 0 and a value of the mmvd merge flag being equal to 0, merge index information for the regular merge mode is included in the merge data syntax.
2 . An image encoding method performed by an encoding apparatus, the image encoding method comprising: determining an inter prediction mode of a current block and generating inter prediction mode information indicating the inter prediction mode; generating a merge candidate list of the current block based on the inter prediction mode; generating selection information indicating one of candidates included in the merge candidate list; and encoding image information including the inter prediction mode information and the selection information, wherein the image information includes a first enabled flag for a combined inter-picture merge and intra-picture prediction (CIIP) mode and a second enabled flag for a partitioning prediction mode, wherein for the partitioning prediction mode, prediction is performed by partitioning a block, wherein the partitioning includes triangle partitioning, wherein a merge data syntax is related to the inter prediction mode information, wherein the merge data syntax included in the image information includes at least one of a regular merge flag related to whether a regular merge mode is applied to the current block, an mmvd merge flag related to whether a merge mode with motion vector difference (MMVD) is applied to the current block and a merge subblock flag related to whether a subblock merge mode is applied to the current block, wherein a parsing order of the regular merge flag precedes a parsing order of the mmvd merge flag, and wherein, based on a value of the first enabled flag being equal to 0, a value of the second enabled flag being equal to 0, the regular merge flag, which indicates a value of 1, being not present, a value of the merge subblock flag being equal to 0 and a value of the mmvd merge flag being equal to 0, merge index information for the regular merge mode is included in the merge data syntax.
3 . A transmission method of data for an image, the method comprising: generating a bitstream for the image, wherein the bitstream is generated based on determining an inter prediction mode of a current block and generating inter prediction mode information indicating the inter prediction mode, generating a merge candidate list of the current block based on the inter prediction mode, generating selection information indicating one of candidates included in the merge candidate list, and encoding image information including the inter prediction mode information and the selection information; and transmitting the data comprising the bitstream, wherein the image information includes a first enabled flag for a combined inter-picture merge and intra-picture prediction (CIIP) mode and a second enabled flag for a partitioning prediction mode, wherein for the partitioning prediction mode, prediction is performed by partitioning a block, wherein the partitioning includes triangle partitioning, wherein a merge data syntax is related to the inter prediction mode information, wherein the merge data syntax included in the image information includes at least one of a regular merge flag related to whether a regular merge mode is applied to the current block, an mmvd merge flag related to whether a merge mode with motion vector difference (MMVD) is applied to the current block and a merge subblock flag related to whether a subblock merge mode is applied to the current block, wherein a parsing order of the regular merge flag precedes a parsing order of the mmvd merge flag, and wherein, based on a value of the first enabled flag being equal to 0, a value of the second enabled flag being equal to 0, the regular merge flag, which indicates a value of 1, being not present, a value of the merge subblock flag being equal to 0 and a value of the mmvd merge flag being equal to 0, merge index information for the regular merge mode is included in the merge data syntax.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. application Ser. No. 18/115,883 filed on Mar. 1, 2023, which is a continuation of U.S. application Ser. No. 17/555,190 filed on Dec. 17, 2021, which is a National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2020/007944, filed on Jun. 19, 2020, which claims the benefit of U.S. Provisional Application No. 62/863,810 filed on Jun. 19, 2019, the contents of which are all hereby incorporated by reference herein in their entirety. BACKGROUND OF THE DISCLOSURE Field of the Disclosure The present disclosure relates to an image decoding method for performing inter prediction when a prediction mode is not finally selected for a current block, and an apparatus thereof. Related Art Recently, the demand for high resolution, high quality image/video such as 4K, 8K or more Ultra High Definition (UHD) image/video is increasing in various fields. As the image/video resolution or quality becomes higher, relatively more amount of information or bits are transmitted than for conventional image/video data. Therefore, if image/video data are transmitted via a medium such as an existing wired/wireless broadband line or stored in a legacy storage medium, costs for transmission and storage are readily increased. Moreover, interests and demand are growing for virtual reality (VR) and artificial reality (AR) contents, and immersive media such as hologram; and broadcasting of images/videos exhibiting image/video characteristics different from those of an actual image/video, such as game images/videos, are also growing. Therefore, a highly efficient image/video compression technique is required to effectively compress and transmit, store, or play high resolution, high quality images/videos showing various characteristics as described above. SUMMARY The present disclosure provides a method and apparatus for increasing image coding efficiency. The present disclosure also provides a method and apparatus for deriving a prediction sample based on a default merge mode. The present disclosure also provides a method and apparatus for deriving a prediction sample by applying a regular merge mode as a default merge mode. In an aspect, an image decoding method performed by a decoding apparatus is provided. The method includes: receiving image information including inter prediction mode information through a bit stream; generating a merge candidate list of a current block based on the inter prediction mode information; deriving motion information of the current block based on a candidate selected from the merge candidate list; and generating prediction samples of the current block based on the motion information, wherein a regular merge mode is applied to the current block based on that a merge mode is available for the current block based on the general merge flag and a merge mode with motion vector difference (MMVD) mode, a merge subblock mode, a combined inter-picture merge and intra-picture prediction (CIIP) mode, and a partitioning mode in which prediction is performed by dividing the current block into two partitions are not available, and the merge candidate list is generated by applying the regular merge mode to the current block. In an aspect, an image encoding method performed by an encoding apparatus is provided. The method includes: determining an inter prediction mode of a current block and generating inter prediction mode information indicating the inter prediction mode; generating a merge candidate list of the current block based on the inter prediction mode; generating selection information indicating one of candidates included in the merge candidate list; and encoding image information including the inter prediction mode information and the selection information, wherein a regular: merge mode is applied to the current block based on that a merge mode is available for the current block based on the general merge flag and a merge mode with motion vector difference (MMVD) mode, a merge subblock mode, a combined inter-picture merge and intra-picture prediction (CIIP) mode, and a partitioning mode in which prediction is performed by dividing the current block into two partitions are not available, and the merge candidate list is generated by applying the regular merge mode to the current block. In another aspect, there is provided a computer-readable storage medium storing encoded information causing an image decoding apparatus to perform an image decoding method, wherein the image decoding method includes: acquiring image information including inter prediction mode information and residual information through a bitstream; generating a merge candidate list of a current block based on the inter prediction mode information; deriving motion information of the current block based on a candidate selected from the merge candidate list; and generating prediction samples of the current block based on the motion information, wherein a