Variable Length Code Allocation for Intra Prediction Modes
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Solution Overview
Problem
Existing image compression methods, such as H.264/AVC, do not efficiently compress intra prediction information when the intra prediction mode of a current block does not correspond to that of adjacent blocks, leading to reduced compression efficiency due to increased calculation and decreased accuracy.
Innovation Solution
A method using variable length codes to encode intra prediction modes, where the Most Probable Mode (MPM) is determined among adjacent blocks, and codes are allocated in ascending order based on similarity, allowing efficient compression even when the current block's mode does not match the MPM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed length codes are used to encode intra prediction modes, then encoding simplicity is maintained, but compression efficiency decreases when current block mode differs from adjacent block modes
Solution Approach 1:
The patent changes the encoding parameter from fixed length codes to variable length codes. Variable length codes adaptively assign shorter code lengths to frequently occurring modes (those similar to adjacent blocks) and longer code lengths to less frequent modes, thereby improving compression efficiency while maintaining manageable encoding complexity through systematic code allocation
Solution Approach 2:
The patent applies local quality by determining the most probable mode (MPM) based on adjacent block characteristics and using this local information to guide the variable length code allocation. Each current block's encoding is optimized based on its specific local context (adjacent block modes), rather than applying a uniform encoding scheme across all blocks
2Productivity
If variable length codes are used to encode intra prediction modes, then compression efficiency improves, but calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-determining the most probable mode (MPM) from adjacent blocks before encoding the current block. This preliminary determination of which mode is most likely allows the encoder to systematically allocate variable length codes in ascending order of probability, reducing the calculation complexity during actual encoding while maintaining high compression efficiency
3Productivity
If intra prediction mode is encoded without reference to adjacent blocks, then encoding speed is maintained, but compression efficiency decreases due to increased bitstream length
Solution Approach 1:
The patent implements feedback by using the intra prediction modes of adjacent blocks (which have already been encoded) as reference information for encoding the current block. This feedback mechanism allows the encoder to exploit spatial redundancy in the image data, improving compression efficiency without significantly increasing encoding time since the adjacent block modes are already available from previous encoding steps
Data Source
AI summary
The disclosure relates to a method, apparatus, and recording medium for encoding an intra-prediction mode of an image using variable length codes, including: determining an intra prediction mode of a current block; determining an intra prediction mode having smallest mode number among intra prediction modes of encoded adjacent blocks as Most Probable Mode; generating and allocating variable length codes in ascending order from shorter code with higher similarity for directivity with MPM for all intra-prediction modes; and encoding intra prediction mode of current block based on allocated variable length codes, and thereby generates efficient variable length codes in consideration of high correlation in the intra-prediction modes of current block and peripheral blocks even if intra-prediction mode of current block does not match MPM derived with reference to peripheral blocks, and efficiently compressing information on intra-prediction mode of current block using variable length codes, thereby improving intra video encoding performance.