Image Decoding Device Chroma Quantization Matrix Segmentation
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Solution Overview
Problem
The existing High Efficiency Video Coding (HEVC) method does not support control of quantization according to frequency components when using integrated chroma residual coefficient coding, which limits the improvement of subjective image quality.
Innovation Solution
An image decoding device that performs inverse quantization using a quantization matrix, allowing prediction errors for the chroma component to be derived by omitting the encoding of first quantized transform coefficients associated with a specific chroma component and using those of a different chroma component, enabling independent quantization control for each frequency component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integrated chroma residual coefficient coding is used to improve coding efficiency, then compression ratio is improved, but quantization control according to frequency components is lost and subjective image quality deteriorates
Solution Approach 1:
The patent segments the chroma components into a first chroma component and a second chroma component. The first chroma component uses integrated coding with the luma component, while the second chroma component uses separate coding with its own quantization matrix. This segmentation allows different quantization strategies for different chroma components, maintaining frequency-based quantization control for the second component while achieving compression benefits from integrated coding for the first component.
Solution Approach 2:
The patent applies different quantization quality levels to different chroma components. The second chroma component is quantized using a dedicated quantization matrix that allows frequency-based control, ensuring high quality where needed. The first chroma component uses a simplified quantization approach compatible with integrated coding. This local quality differentiation resolves the contradiction by providing high quantization precision for specific components while maintaining overall coding efficiency.
2Manufacturing precision
If a dedicated quantization matrix for the first chroma component is introduced to improve subjective image quality, then quantization control is restored, but device complexity increases
Solution Approach 1:
The patent makes the second quantization matrix (dedicated to the second chroma component) serve multiple functions: it performs quantization for the second chroma component and also serves as the quantization matrix for the first chroma component in the integrated coding path. This multi-functionality reduces the total number of quantization matrices needed, thereby reducing device complexity while still providing dedicated quantization control for frequency-based processing.
Solution Approach 2:
Instead of maintaining separate dedicated quantization matrices for both chroma components (which would increase complexity), the patent discards the need for a separate first quantization matrix by recovering and reusing the second quantization matrix for both components. This reduces the number of matrices to be stored and processed, lowering device complexity while preserving the ability to control quantization for the second component.
3Manufacturing precision
If separate quantization matrices are used for luma and chroma components to maintain image quality, then subjective image quality is preserved, but coding efficiency decreases
Solution Approach 1:
The patent introduces dynamic switching capability that allows the encoder to select between different coding modes for the first chroma component: integrated coding with luma (when compression is prioritized) or separate coding with dedicated quantization (when quality is prioritized). This dynamic approach allows the system to adapt to different content and quality requirements, achieving high coding efficiency when using integrated mode while preserving the option to use separate quantization matrices when quality preservation is critical.
Data Source
AI summary
An image coding device that suppresses degradation of subjective image quality while improving the coding efficiency of residual coefficients of two chroma components. The image coding device that codes image data constituted by one luma component and two chroma components, comprises quantizing unit that performs an orthogonal transform on each of components of a block obtained by dividing an image to be coded, and quantizes transform coefficients of each of the components obtained from the orthogonal transform; and coding unit that codes residual coefficients obtained by the quantizing unit, wherein when coding the transform coefficients of the orthogonal transform of the two chroma components in an integrated manner, the coding unit quantizes transform coefficients of the orthogonal transform obtained from the integration using a predetermined quantization matrix, and codes residual coefficients obtained from the quantizing.