Reference-Line Intra-Prediction Mode Derivation for Planar MPM Coding

The patent implements dynamic selection of intra-prediction mode derivation methods based on block characteristics. The encoder determines whether to apply the extended MPM list derivation (which improves efficiency) or conventional derivation (which maintains simplicity) by evaluating block size, position, and neighboring block modes. This dynamic adaptation allows the system to achieve high coding efficiency for suitable blocks while maintaining low complexity for others, directly resolving the contradiction between productivity and device complexity.

The patent applies local quality by making the MPM list composition block-specific rather than uniform across all blocks. The planar mode is selectively included in the MPM list based on local characteristics such as block size, block position in the picture, and the intra-prediction modes of neighboring blocks. For blocks where planar mode is likely to be optimal, it is included in the MPM list to improve prediction accuracy. For other blocks, the MPM list excludes planar mode to reduce signaling overhead, thereby achieving high prediction accuracy where needed while controlling overall bitrate.

The patent implements partial action by applying the extended MPM list derivation method selectively to only those blocks that benefit most from it, rather than universally to all blocks. The encoder evaluates specific conditions (block size thresholds, position-dependent criteria, neighboring block mode patterns) and applies the computationally intensive extended derivation only when these conditions are met. For blocks not meeting the criteria, the simpler conventional derivation is used. This partial application achieves improved compression performance for critical blocks while maintaining acceptable processing times overall, effectively resolving the contradiction between productivity and loss of time.