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 the Versatile Video Coding standard, then the decoding process follows the standard specification, but the quantization parameter may become negative which causes instability in inverse quantization processing
Solution Approach 1:
The patent applies preliminary anti-action by predicting the quantization parameter from neighboring blocks before actual decoding occurs. This prediction mechanism prevents negative values from occurring in the first place, thereby ensuring stability in inverse quantization processing without requiring complex post-correction mechanisms.
Solution Approach 2:
The patent changes the parameter derivation method from direct standard-compliant decoding to a prediction-based approach. By using spatial correlation with neighboring blocks to predict the quantization parameter, the system transforms the parameter obtaining process into a more reliable operation that inherently avoids negative values while maintaining computational efficiency.
2Productivity
If adaptive color transform is applied to improve coding efficiency, then the compression performance is enhanced, but the quantization parameter may become negative which degrades the reliability of decoding
Solution Approach 1:
The patent performs preliminary action by deriving the quantization parameter through prediction from neighboring blocks before the adaptive color transform is applied. This pre-derivation ensures that a reliable, non-negative quantization parameter is established in advance, allowing the adaptive color transform to proceed with enhanced coding efficiency without compromising the reliability of the quantization parameter.
3Reliability
If the quantization parameter is corrected to ensure non-negative values, then the reliability of inverse quantization is improved, but additional processing steps are required which increases device complexity
Solution Approach 1:
The patent performs the correction action preliminarily by predicting the quantization parameter from neighboring blocks before decoding. This approach ensures that the quantization parameter is non-negative from the outset, eliminating the need for complex post-correction mechanisms and reducing the overall device complexity while maintaining high reliability.
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.