Chroma Intra-Prediction Scaling for Efficient Image Decoding
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Solution Overview
Problem
The existing MPEG-4 AVC/H.264 compression coding system faces inefficiencies in coding and decoding processes, particularly when intra-prediction modes are not aligned with color-difference formats, leading to degraded process efficiency.
Innovation Solution
A picture coding device and method that sets prediction blocks for both brightness and color-difference signals, using intra-brightness and intra-color-difference prediction modes to efficiently code and decode signals in conversion blocks, with specific predictors for each signal type, allowing for optimized bitstream coding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intra-prediction modes are not aligned with color-difference formats, then coding flexibility is maintained, but processing efficiency is degraded
Solution Approach 1:
The patent applies local quality by adapting the intra-prediction mode selection and block partitioning strategy to match the specific color-difference format being used. For 4:2:0 format, the color-difference signal blocks are processed with appropriate size adjustments and prediction modes that reflect the subsampled nature of the chroma components, thereby optimizing processing efficiency for each local format condition.
Solution Approach 2:
The patent changes key parameters including block size, partitioning structure, and prediction mode selection based on the color-difference format parameter. When the format changes from 4:2:0 to 4:2:2 or 4:4:4, the system adjusts the chroma block dimensions and prediction algorithms accordingly, allowing the coding process to adapt its parameters to match the input format and improve efficiency.
2Manufacturing precision
If separate intra-prediction modes are used for brightness and color-difference signals, then coding precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the intra-prediction process into separate handling for luma (brightness) and chroma (color-difference) signals. Each signal type can have its own prediction mode and block partitioning strategy, allowing independent optimization of coding precision for each component while maintaining manageable complexity through modular processing.
Solution Approach 2:
The patent creates a universal intra-prediction framework that handles both luma and chroma signals through a common architecture. The same basic prediction mechanisms and block structures are used for both signal types, with format-specific adjustments applied as needed, thereby achieving high coding precision without proportionally increasing decoder complexity.
Data Source
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AI summary
In a picture coding device for coding picture signals including a brightness signal and a color-difference signal in a block unit using intra-prediction and coding information regarding an intra-prediction mode, when aspect ratios of pixels of the brightness signal and the color-difference signal are different from each other, a bitstream generator 113 converts a mode number of a first intra-color-difference prediction mode used when the aspect ratios are equal to each other into a scaled mode number and derives a second intra-color-difference prediction mode used when the aspect ratios are different from each other.