Intra Prediction Decoding With Uniform Cross-Component Down-Sampling
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Solution Overview
Problem
Existing image encoding/decoding technologies face challenges in optimizing down-sampling processes for cross-component prediction, particularly in handling various color formats and sub-sampling factors, leading to inefficiencies and difficulties in implementing software and hardware.
Innovation Solution
The method involves determining intra prediction modes for current blocks, deriving reference sample lengths based on block dimensions, and performing cross-component prediction by generating neighboring samples through down-sampling, with filters adjusted based on sample availability and color signal locations, ensuring accurate prediction even when neighboring samples are unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If various types of down-sampling filters are selectively used according to the location of down-sampling and the effectiveness of neighboring pixels, then cross-component prediction accuracy is improved, but device complexity and difficulty of implementation increase
Solution Approach 1:
The patent changes the parameter of filter selection from location-dependent to uniform across all positions. Instead of selecting different filters based on down-sampling location and neighboring pixel effectiveness, the patent applies a single filter type (e.g., 2x2 average filter) uniformly to all chroma blocks, simplifying the implementation while maintaining adequate prediction accuracy.
Solution Approach 2:
The patent segments the down-sampling process into a standardized two-step procedure: first applying a 2x2 average filter to neighboring luma samples, then performing subsampling. This segmentation creates a modular, easily implementable process that avoids the complexity of selective filter application while maintaining prediction accuracy.
2Reliability
If down-sampling is performed with location-dependent filter selection, then prediction effectiveness is improved, but ease of manufacture and implementation deteriorates
Solution Approach 1:
The patent changes the filter application parameter from variable (location-dependent) to constant (uniform application). This parameter change maintains prediction effectiveness by consistently applying a proven 2x2 average filter, while dramatically improving ease of manufacture and implementation in both software and hardware.
Solution Approach 2:
The patent uses a standardized copying approach where the same filter operation is replicated across all chroma blocks regardless of position. This copying strategy ensures consistent prediction effectiveness while simplifying implementation, as the same code or circuit can be reused for every block without complex conditional logic.
3Adaptability or versatility
If reference sample lengths are derived based on current block dimensions, then adaptability to various block sizes is improved, but device complexity increases
Solution Approach 1:
The patent changes the reference sample length parameter from dynamically calculated to fixed based on block type. For chroma blocks, the reference sample length is set to match the chroma block dimensions directly, eliminating complex calculations while maintaining adaptability to different block sizes through straightforward parameter assignment.
Data Source
AI summary
Disclosed herein is an image encoding/decoding method. A method of decoding an image includes determining an intra prediction mode of a current block, and generating a prediction block of the current block, by performing prediction based on the intra prediction mode. When the intra prediction mode of the current block is a matrix-based intra prediction (MIP) mode, a length of a reference sample used for intra prediction is derived based on a length of the current block.