Color Difference Scaling for High Dynamic Range Encoding
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Solution Overview
Problem
Existing methods for encoding and decoding color-difference components in high dynamic range images introduce quantization noise due to reduced dynamic ranges in certain color spaces, such as ITU Rec709 and ITU Rec2020, which limits the accuracy of color representation.
Innovation Solution
Applying a gain factor to color difference components before encoding to extend their dynamic range within the range -0.5 to 0.5, and including data representative of the gain factor in Video Usability Information for transmission, allowing for scaling prior to or after quantization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color difference components are encoded directly without gain application, then encoding simplicity is maintained, but quantization noise increases and color representation accuracy deteriorates
Solution Approach 1:
The patent applies a gain factor to color difference components before encoding to extend their dynamic range. This preliminary action ensures that the components utilize the full available code range, thereby reducing quantization noise and improving color representation accuracy without adding complex post-processing steps
Solution Approach 2:
The patent changes the dynamic range parameter of color difference components by applying a gain factor. This parameter transformation maps the limited dynamic range of color difference components to a wider range, optimizing the use of available bits and reducing quantization effects while maintaining encoding efficiency
2Measurement precision
If the dynamic range of color difference components is limited by color space definition, then color space compatibility is maintained, but quantization noise increases and measurement precision deteriorates
Solution Approach 1:
The patent applies a gain factor to extend the dynamic range of color difference components beyond the traditional limits of specific color spaces. This parameter change allows the system to utilize the full available code range while maintaining compatibility through proper gain selection based on the target color space
Solution Approach 2:
The patent introduces dynamic range extension through gain application that can be adapted to different color spaces. The gain factor is selected based on the specific color space requirements, allowing the system to dynamically adjust to different color space standards while improving precision
3Measurement precision
If quantization is applied directly to color difference components, then encoding efficiency is maintained, but quantization noise increases and reduces measurement precision
Solution Approach 1:
The patent applies gain extension to color difference components before quantization. This preliminary action ensures that the components are properly scaled to utilize the full available code range, thereby maximizing the effectiveness of quantization and minimizing quantization noise without reducing encoding efficiency
Data Source
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AI summary
The invention concerns scaling color difference components prior to encoding in order to extend the dynamic range. In one embodiment the color difference components are encoded prior to quantisation. In another embodiment the color difference components are encoded after quantisation. A decoder is configured to process data representative of the gain factor for a decoding process.