Chroma Quantization Parameter Table for Image Decoding
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images leads to increased transmission and storage costs due to the high amount of information required, necessitating a more efficient image compression technique.
Innovation Solution
An image decoding method and apparatus that improves coding efficiency by deriving and using a chroma quantization parameter table based on a flag representing the presence of quantization parameter data for combined chroma coding, allowing for efficient coding of residual samples and generation of a reconstructed picture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution and high-quality image data is transmitted or stored, then image quality is improved, but transmission cost and storage cost increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting quantization parameters based on image characteristics. Different quantization parameter tables are selected based on the chroma type and content characteristics, allowing optimal compression ratios while maintaining perceived image quality. This resolves the contradiction by changing the quantization parameters to achieve better compression without visibly degrading image quality.
Solution Approach 2:
The patent implements local quality by applying different quantization strategies to different regions and components of the image. Specifically, it uses separate quantization parameter tables for luma and chroma components, and further differentiates based on chroma type (4:2:0, 4:2:2, 4:4:4). This allows aggressive compression in less sensitive areas while maintaining quality in important regions, reducing overall data量 while preserving image quality.
2Quantity of substance
If conventional compression techniques are used, then transmission and storage costs are reduced, but image quality deteriorates
Solution Approach 1:
The patent overcomes conventional compression limitations by dynamically changing quantization parameters based on actual image content. Instead of using fixed compression ratios, the system selects from multiple quantization parameter tables depending on chroma type and content characteristics, achieving better quality retention at comparable compression ratios.
Solution Approach 2:
The patent introduces dynamics by making the compression process adaptive rather than static. The quantization parameters are not fixed but are selected dynamically based on image characteristics such as chroma type and content complexity. This dynamic adaptation allows the compression system to maintain higher quality at the same compression ratio compared to conventional fixed-parameter methods.
3Measurement precision
If quantization parameter data for combined chroma coding is always transmitted, then coding precision is improved, but data transmission volume increases
Solution Approach 1:
The patent extracts only the necessary quantization parameter data based on the specific chroma type and content characteristics. Instead of always transmitting complete quantization parameter sets, the system selectively transmits only when needed (indicated by the present_flag), removing redundant data while maintaining coding precision where required.
Solution Approach 2:
The patent applies partial action by transmitting quantization parameter data only partially - specifically, only when the present_flag indicates it is needed based on chroma type and content characteristics. This selective transmission provides sufficient precision for the actual content requirements without the overhead of always transmitting complete parameter sets.
Data Source
AI summary
An image decoding method performed by a decoding apparatus according to the present document comprises the steps of: obtaining a flag indicating whether quantization parameter data for combined chroma coding is present on the basis of a type of chroma; obtaining the quantization parameter data for the combined chroma coding on the basis of the flag; deriving a chroma quantization parameter table on the basis of the quantization parameter data; deriving a quantization parameter for the combined chroma coding on the basis of the chroma quantization parameter table; deriving residual samples on the basis of the quantization parameter; and generating a reconstructed picture on the basis of the residual samples.