KR-102964576-B1 - METHOD AND APPARATUS FOR INTRA PREDICTION MODE DERIVATION

Abstract

A method and apparatus for video encoding/decoding are provided. A video decoding method according to the present invention comprises the steps of: deriving an in-frame prediction mode of a current block using an in-frame prediction mode of a neighboring block adjacent to the current block; constructing a reference sample for the current block; and performing an in-frame prediction for the current block using the in-frame prediction mode and the reference sample. The step of deriving an in-frame prediction mode of the current block includes the step of constructing an MPM list based on whether the in-frame prediction mode of the current block is a Planar mode.

Inventors

• 이진호
• 강정원
• 이하현
• 임성창
• 김휘용

Assignees

• 한국전자통신연구원

Dates

Publication Date

20260513

Application Date

20191227

Priority Date

20181228

Claims (20)

1. A step of obtaining a flag from the bitstream indicating whether the in-screen prediction mode of the current block is not a planner mode; A step of inducing an in-screen prediction mode of the current block based on the above flag; A step of generating a reference sample for the above current block; and The method includes the step of predicting the current block based on the prediction mode within the screen and the reference sample, wherein In response to the above flag indicating that the in-screen prediction mode is not a planner mode, the in-screen prediction mode is derived based on an MPM list, and In response to the above flag indicating that the in-screen prediction mode is a planner mode, the in-screen prediction mode is guided to a planner mode without deriving the MPM list, and The above MPM list is derived by comparing a prediction mode candidate within the first screen and a prediction mode candidate within the second screen, and The above-mentioned first in-screen prediction mode candidate is obtained based on the in-screen prediction mode of the left neighbor block of the above-mentioned current block, and The above second in-screen prediction mode candidate is obtained based on the in-screen prediction mode of the upper neighbor block of the above current block, and A video decoding method characterized in that, in response to the fact that the first in-screen prediction mode candidate is identical to the second in-screen prediction mode candidate and the index value of the first in-screen prediction mode candidate and the index value of the second in-screen prediction mode candidate are both less than or equal to 1, the MPM list is composed of a DC mode, a vertical direction mode, a horizontal direction mode, an in-screen prediction mode having an index value of 46, and an in-screen prediction mode having an index value of 54.
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3. In paragraph 1, An image decoding method characterized by the number of in-frame prediction mode candidates in the above MPM list being fixed at 5.
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10. In paragraph 1, An image decoding method characterized in that the current block is divided into a predetermined number of sub-blocks based on at least one of the size and shape of the current block.
11. Step of determining the in-screen prediction mode of the current block; A step of generating a reference sample for the above current block; The method includes the step of predicting the current block based on the prediction mode within the screen and the reference sample, wherein A flag indicating whether the in-screen prediction mode of the current block is not a planner mode is encoded as a bitstream, and In response to the fact that the above-mentioned in-screen prediction mode is not a planner mode, the above-mentioned in-screen prediction mode is encoded based on an MPM list, and In response to the prediction mode within the above screen being planner mode, the above MPM list is not derived, and The above MPM list is derived by comparing a prediction mode candidate within the first screen and a prediction mode candidate within the second screen, and The above-mentioned first in-screen prediction mode candidate is obtained based on the in-screen prediction mode of the left neighbor block of the above-mentioned current block, and The above second in-screen prediction mode candidate is obtained based on the in-screen prediction mode of the upper neighbor block of the above current block, and A video encoding method characterized in that, in response to the fact that the first in-frame prediction mode candidate is identical to the second in-frame prediction mode candidate and the index value of the first in-frame prediction mode candidate and the index value of the second in-frame prediction mode candidate are both less than or equal to 1, the MPM list is composed of a DC mode, a vertical direction mode, a horizontal direction mode, an in-frame prediction mode having an index value of 46, and an in-frame prediction mode having an index value of 54.
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13. In Paragraph 11, A video encoding method characterized by the number of in-frame prediction mode candidates in the above MPM list being fixed at 5.
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20. As a non-transient computer-readable recording medium storing a bitstream encoded by a video encoding method, The above image encoding method is, Step of determining the in-screen prediction mode of the current block; A step of generating a reference sample for the above current block; The method includes the step of predicting the current block based on the prediction mode within the screen and the reference sample, wherein A flag indicating whether the in-screen prediction mode of the current block is not a planner mode is encoded in the bitstream, and In response to the fact that the above-mentioned in-screen prediction mode is not a planner mode, the above-mentioned in-screen prediction mode is encoded based on an MPM list, and In response to the prediction mode within the above screen being planner mode, the above MPM list is not derived, and The above MPM list is derived by comparing a prediction mode candidate within the first screen and a prediction mode candidate within the second screen, and The above-mentioned first in-screen prediction mode candidate is obtained based on the in-screen prediction mode of the left neighbor block of the above-mentioned current block, and The above second in-screen prediction mode candidate is obtained based on the in-screen prediction mode of the upper neighbor block of the above current block, and A non-transient computer-readable recording medium characterized in that, in response to the first in-screen prediction mode candidate being identical to the second in-screen prediction mode candidate and the index value of the first in-screen prediction mode candidate and the index value of the second in-screen prediction mode candidate both being less than or equal to 1, the MPM list comprises a DC mode, a vertical direction mode, a horizontal direction mode, an in-screen prediction mode having an index value of 46, and an in-screen prediction mode having an index value of 54.

Description

Method and apparatus for inducing intra prediction mode The present invention relates to an image encoding/decoding method, an apparatus, and a recording medium storing a bitstream. Specifically, the present invention relates to an image encoding/decoding method and apparatus using in-frame prediction, and a recording medium storing a bitstream generated by the image encoding method or apparatus of the present invention. Recently, the demand for high-resolution, high-quality video, such as HD (High Definition) and UHD (Ultra High Definition) video, has been increasing across various application fields. As video data becomes higher in resolution and quality, the relative volume of data increases compared to conventional video data; consequently, transmission and storage costs increase when video data is transmitted using existing wired or wireless broadband lines or stored using existing storage media. To address these issues arising from the increase in video data resolution and quality, high-efficiency video encoding and decoding technologies for video with higher resolution and quality are required. Various video compression technologies exist, such as inter-frame prediction technology that predicts pixel values in the current picture from previous or subsequent pictures, intra-frame prediction technology that predicts pixel values in the current picture using pixel information within the current picture, transformation and quantization technology for compressing the energy of residual signals, and entropy coding technology that assigns short codes to values with high frequency and long codes to values with low frequency; by utilizing these video compression technologies, video data can be effectively compressed for transmission or storage. FIG. 1 is a block diagram showing the configuration according to one embodiment of an encoding device to which the present invention is applied. FIG. 2 is a block diagram showing the configuration according to one embodiment of a decoding device to which the present invention is applied. Figure 3 is a diagram schematically showing the segmentation structure of an image when encoding and decoding an image. Figure 4 is a diagram illustrating an example of an in-screen prediction process. Figure 5 is a diagram illustrating an example of an inter-frame prediction process. Figure 6 is a diagram illustrating the process of transformation and quantization. Figure 7 is a diagram illustrating reference samples available for in-screen prediction. FIG. 8 is a flowchart illustrating an in-screen prediction process according to an embodiment of the present invention. FIG. 9 is a diagram illustrating the relationship between a luminance block and a color difference block according to an embodiment of the present invention. FIG. 10 is a drawing for illustrating referenceable surrounding blocks to induce an in-screen prediction mode of a current block according to an embodiment of the present invention. FIG. 11 is a diagram illustrating an in-screen prediction mode according to an embodiment of the present invention. FIGS. 12 to 18 are drawings for explaining the process of configuring an MPM list according to an embodiment of the present invention. FIG. 19 is a diagram illustrating the process of signaling an in-screen prediction mode according to an embodiment of the present invention. FIG. 20 is a diagram illustrating DC prediction according to the size and/or shape of the current block according to one embodiment of the present invention. FIG. 21 is a diagram illustrating the process of performing in-screen prediction between color components according to one embodiment of the present invention. The present invention is susceptible to various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals in the drawings refer to the same or similar functions across various aspects. The shapes and sizes of elements in the drawings may be exaggerated for clearer explanation. The detailed description of exemplary embodiments described below refers to the accompanying drawings, which illustrate specific embodiments as examples. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments. It should be understood that various embodiments are different but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in relation to one embodiment. Furthermore, it should be understood that the location or arrangement of individual comp