BDPCM Constraint Flag for Image Decoding Efficiency
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images leads to a significant increase in the amount of information to be transmitted and stored, resulting in higher transmission and storage costs.
Innovation Solution
The proposed method and apparatus improve image coding efficiency by signaling a Block-based Delta Pulse Code Modulation (BDPCM) flag based on the size of the current block and the maximum transform block size, allowing for efficient determination of whether to apply BDPCM, thereby reducing bit amounts and enhancing overall coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If BDPCM is applied to all blocks regardless of size, then compression efficiency is improved, but bit amount for signaling increases
Solution Approach 1:
The patent applies BDPCM selectively based on local block size characteristics. Different blocks receive different BDPCM treatment according to their size: smaller blocks use BDPCM while larger blocks use alternative methods. This local differentiation improves overall compression efficiency without unnecessarily signaling BDPCM for all blocks, thus reducing the bit amount for signaling.
2Loss of information
If a single syntax element is used to signal BDPCM constraint for the entire image, then signaling overhead is reduced, but flexibility in applying BDPCM to different block sizes is limited
Solution Approach 1:
The patent introduces a dynamic interpretation mechanism where a single syntax element (bdpcm_constraint_flag) adapts its meaning based on the current block size. When the block size is smaller than or equal to the maximum transform block size, the flag directly controls BDPCM application. When the block size exceeds the maximum transform block size, the flag's effect is overridden. This dynamic behavior provides both low signaling overhead and flexibility for different block sizes.
3Loss of energy
If BDPCM is constrained for high-resolution images, then transmission cost is reduced, but image quality may deteriorate
Solution Approach 1:
The patent applies BDPCM constraint selectively based on block size rather than uniformly across the entire high-resolution image. Small blocks (size ≤ maximum transform block size) are subject to BDPCM constraint for compression, while larger blocks are excluded from BDPCM to maintain quality. This local differentiation reduces transmission cost for compressible regions while preserving image quality in regions where BDPCM might degrade performance.
Data Source
AI summary
An image decoding method performed by a decoding apparatus, according to the present document, comprises the steps of: acquiring image information including a block-based delta pulse code modulation (BDPCM) constraint flag indicating whether or not BDPCM is constrained with respect to an image; acquiring BDPCM-associated information regarding a current block on the basis of the BDPCM constraint flag; and generating reconstructed samples for the current block on the basis of the BDPCM-associated information.