Image Decoding Quantization Parameter Correction for Non-Negative QP
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Solution Overview
Problem
In Versatile Video Coding (Draft 7), JVET-N 1001, the decoded quantization parameter can have negative values, which is undesirable.
Innovation Solution
An image decoding device and method that corrects the decoded quantization parameter based on whether adaptive color transform is applied to a target block, ensuring the quantization parameter is always 0 or more, using a quantization parameter deriving unit to set the larger of the corrected value and a predetermined value of 0 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the decoded quantization parameter is used directly from Versatile Video Coding (Draft 7), then the decoding process follows the standard specification, but the quantization parameter may become negative which causes calculation instability and incorrect results
Solution Approach 1:
The patent applies preliminary anti-action by detecting potential negative quantization parameter values before they cause calculation errors, and applying correction in advance. The quantization parameter deriving unit checks if the decoded QP is negative and applies offset correction before the QP is used in subsequent decoding operations, preventing the harmful effect of negative values on calculation stability.
2Productivity
If adaptive color transform is applied to target blocks, then coding efficiency is improved, but the quantization parameter calculation may produce negative values that require correction
Solution Approach 1:
The patent applies local quality by making the quantization parameter correction dependent on the specific block characteristics. The quantization parameter deriving unit determines whether adaptive color transform is applied to each target block and applies different correction logic accordingly. This ensures that the quantization parameter is accurately adjusted based on local block properties while maintaining overall coding efficiency.
Data Source
AI summary
An image decoding device includes a quantization parameter deriving unit configured to correct a value of a decoded quantization parameter of a target block depending on whether or not adaptive color transform has been applied to the target block, and then set, as the quantization parameter of the target block, the larger of the corrected value of the quantization parameter and a predetermined value of “0” or more.