BDPCM Image Coding Without Inverse Non-Separable Transform
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images/videos, particularly in immersive media formats, leads to higher transmission and storage costs due to increased bit amounts, necessitating a more efficient image/video compression technique.
Innovation Solution
An image coding method utilizing BDPCM (block differential pulse coded modulation) that applies BDPCM to luma and chroma components, infers transform index and skip flag values as 0, and performs inverse non-separable transforms only when necessary, enhancing coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image coding methods are used for high-resolution images/videos, then image quality is maintained, but transmission and storage costs increase due to increased bit amounts
Solution Approach 1:
The image block is divided into luma component and chroma component for separate BDPCM processing. This segmentation allows different compression strategies to be applied to different color components, optimizing the balance between quality and bit rate reduction.
Solution Approach 2:
The patent applies BDPCM (block differential pulse coded modulation) to transform the coding parameters from absolute pixel values to differential values. This parameter transformation enables more efficient compression by exploiting spatial redundancy within blocks, thereby reducing bit amount while maintaining image quality.
2Productivity
If BDPCM is applied to current block, then coding efficiency is improved, but transform index and skip flag coding complexity increases
Solution Approach 1:
The patent extracts and processes transform index and skip flag information separately from the main BDPCM coding process. By isolating these control parameters, the system can optimize their encoding independently, reducing overall coding complexity while maintaining efficiency gains from BDPCM.
Solution Approach 2:
The transform index and skip flag values are predetermined and inferred based on block characteristics before full encoding begins. This preliminary determination simplifies the main coding process by pre-resolving certain parameter decisions, thereby reducing runtime complexity.
3Reliability
If inverse non-separable transform is applied when BDPCM is used, then processing completeness is achieved, but processing time and complexity increase
Solution Approach 1:
The application of inverse non-separable transform is made dynamic and conditional rather than universal. The transform is applied only when specifically required by the coding mode, allowing the system to adapt processing complexity to actual needs, thereby reducing unnecessary processing time while maintaining completeness when needed.
Solution Approach 2:
The patent implements a skip mechanism where the inverse non-separable transform is bypassed when BDPCM is applied and transform is not required. This selective skipping eliminates redundant processing steps, significantly reducing processing time for cases where the transform would not contribute to coding efficiency.
Data Source
AI summary
An image decoding method according to the present document comprises the steps of: deriving a quantized transform coefficient for a current block on the basis of BDPCM; deriving a transform coefficient by performing dequantization on the quantized transform coefficient; and deriving a residual sample on the basis of the transform coefficient, wherein, when the BDPCM is applied to the current block, inverse non-separable transform is not applied to the transform coefficient.