Intra Luma Prediction Mode Coding Efficiency
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Solution Overview
Problem
Current video coding standards, such as HEVC, do not fully exploit the correlations between neighboring intra luma prediction modes, leading to inefficient coding of intra luma prediction modes, particularly for larger block sizes where the number of prediction modes is high, resulting in substantial side information transmission.
Innovation Solution
The method introduces multiple intra prediction mode candidates based on neighboring blocks, allowing for improved prediction by using the minimum and maximum of neighboring modes, and includes the plane or planar mode as a candidate, with adaptive coding tables and priority reordering to enhance prediction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple intra prediction modes are used to exploit spatial features, then prediction accuracy is improved, but the number of side information bits increases
Solution Approach 1:
The patent derives mode candidates from neighboring blocks before encoding the current block's prediction mode. By pre-establishing a candidate list based on spatial correlation, the encoder reduces the search space and enables more efficient coding of the actual prediction mode, thus improving prediction accuracy while controlling side information overhead.
Solution Approach 2:
The patent dynamically adjusts the prediction mode coding strategy by comparing the current block's prediction mode against derived candidates. When a match is found, compact coding is used; otherwise, full mode information is transmitted. This dynamic adaptation optimizes the balance between prediction accuracy and side information transmission based on actual block characteristics.
2Productivity
If the number of intra luma prediction modes is increased for larger block sizes, then spatial prediction efficiency is improved, but the complexity of mode coding increases
Solution Approach 1:
The patent segments the set of available prediction modes into a smaller subset of candidates derived from neighboring blocks. Instead of directly coding from the full mode set (34 modes for large blocks), the encoder first identifies relevant candidates from spatial neighbors, then selects from this reduced set, thereby reducing coding complexity while maintaining prediction efficiency.
Solution Approach 2:
The patent changes the parameter of mode representation by using candidate indices relative to neighboring blocks rather than absolute mode indices. This transformation reduces the effective mode space that must be coded, simplifying the coding process for large blocks while preserving the ability to represent all necessary prediction directions.
3Reliability
If mode candidates are derived from neighboring blocks, then the probability of mode matching increases, but the coding scheme complexity increases
Solution Approach 1:
The patent employs feedback by using reconstructed neighboring block modes to generate candidates for the current block. This feedback loop exploits spatial correlation, where previously decoded neighbor information informs the coding of the current block, increasing match probability while the feedback mechanism itself is integrated into the standard decoding process.
Solution Approach 2:
The patent introduces mode candidates as an intermediary between neighboring block modes and the current block's prediction mode. Rather than directly comparing current mode with all possible modes, the candidate list acts as an intermediate set that bridges spatial correlation and current block requirements, simplifying the matching process while improving accuracy.
Data Source
AI summary
A method and apparatus for improved intra prediction mode coding are disclosed. Intra prediction exploits the spatial correlation within a picture or within a picture region. In High-Efficiency Video Coding (HEVC), a coding scheme for the intra luma prediction mode is considered, where the intra prediction mode of a current block is compared with the minimum of two intra luma prediction modes corresponding to two neighboring blocks. If the intra prediction mode of the current block is the same as the minimum of the two neighboring intra luma prediction modes, a single bit is transmitted to indicate the case. Otherwise, information for the current intra prediction mode is transmitted in fixed-length codeword. The present invention provides multiple intra prediction mode candidates based on neighboring intra prediction modes so that there is a better chance for predictor hit. Accordingly, improved coding efficiency is achieved.