Screen Content Coding Mode Prediction Adaptation
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Solution Overview
Problem
In the High Efficiency Video Coding (HEVC) standard, the current method for intra mode coding is inefficient for Screen Content Coding (SCC) extensions, as it often results in a default list of most probable modes (MPMs) that are unsuited for coding screen content, leading to increased data rates and reduced coding efficiency due to frequent occurrence of horizontal and vertical modes in graphical content.
Innovation Solution
The method involves determining the most probable modes for a current block by considering neighbor blocks encoded using screen content coding modes, specifically using horizontal or vertical modes if available, and adjusting the derivation of MPMs to prioritize these modes over planar and DC modes, thereby optimizing the prediction mode encoding for screen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the current HEVC intra mode coding method is used, then the coding process is simple, but the coding efficiency is poor for screen content due to default MPM lists being unsuited for graphical content
Solution Approach 1:
The MPM list is made dynamic by adapting its composition based on the coding mode of neighbor blocks. When screen content coding modes are detected in neighbor blocks, the MPM list is reconfigured to prioritize horizontal and vertical modes, transforming the static default list into a context-adaptive structure that improves coding efficiency for graphical content
Solution Approach 2:
The parameters defining the MPM list are changed based on the coding context. Specifically, the mode indices and priorities in the MPM list are adjusted according to whether neighbor blocks use screen content coding modes, allowing the system to switch between default and optimized MPM configurations without fundamental structural changes
2Loss of energy
If horizontal and vertical modes are prioritized for screen content, then the bitrate is reduced, but the complexity of mode determination increases
Solution Approach 1:
The coding mode of neighbor blocks is determined in advance during the encoding process, and this information is used to pre-configure the appropriate MPM list before encoding the current block. This preliminary determination of neighbor block modes allows the system to select the optimal MPM list configuration without adding significant computational overhead during the actual mode decision process
Solution Approach 2:
The encoding process itself generates the information needed to optimize subsequent encoding decisions. By using the coding mode information from already-encoded neighbor blocks, the system automatically determines the appropriate MPM list configuration, eliminating the need for separate complexity-intensive analysis of screen content characteristics
Data Source
AI summary
The present invention concerns a method for encoding an image, comprising the encoding of mode information representing a prediction mode for encoding a current block of pixels according to an Intra coding mode, the method comprising for the determination of set of most probable modes defining at least one candidate for a most probable mode to be the mode information of a neighbor-block if it exists; wherein a candidate for a most probable mode is the horizontal or vertical mode information if this neighbor-block exists and has been encoded using a predetermined coding mode.