Video Coding Loop Scaling for HDR Luminance Control
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Solution Overview
Problem
Current video coding technologies face challenges in efficiently processing video data with non-uniformly distributed perceived just noticeable difference (signal to noise ratio) over its dynamic range, particularly in high dynamic range (HDR) and wide color gamut (WCG) applications, leading to suboptimal compression and quality issues.
Innovation Solution
The implementation of scaling techniques in the video coding loop, where a scaling parameter is determined for video blocks to adjust the dynamic range of luminance values, either increasing or decreasing it depending on the encoding or decoding process, to align with the human visual system's perception and improve signal-to-noise ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If video data is coded using standard dynamic range processing, then compression efficiency is maintained, but perceptual quality deteriorates for HDR content with non-uniform signal-to-noise ratio distribution
Solution Approach 1:
The patent applies dynamic range scaling within the video coding loop by determining a scaling parameter for each block and applying it to scale pixel values. This dynamic adjustment of the dynamic range allows the encoder to optimize perceptual quality for HDR content while maintaining compression efficiency, resolving the contradiction between these two objectives.
Solution Approach 2:
The patent changes the dynamic range parameter of the video data by applying a scaling parameter to the pixel values within the coding loop. This parameter change transforms the video data to have a modified dynamic range that better aligns with human visual perception for HDR content, improving perceptual quality without sacrificing compression efficiency.
2Measurement precision
If the dynamic range of luminance values is increased to match HDR content, then perceptual quality improves, but quantization noise distribution becomes non-uniform
Solution Approach 1:
The patent applies a scaling parameter to change the dynamic range of luminance values in each block, which improves perceptual quality for HDR content. The scaling is applied within the coding loop before quantization, ensuring that the quantization process operates on appropriately scaled values that achieve uniform noise distribution in the perceptual domain.
Solution Approach 2:
The patent replaces the standard quantization mechanism with a scaled quantization mechanism that operates on dynamically range-scaled pixel values. This substitution ensures that quantization noise is uniformly distributed across the perceptual dynamic range, resolving the contradiction between improved perceptual quality and uniform noise distribution.
3Productivity
If block-based processing is applied to video data, then compression efficiency is improved, but handling of non-uniform signal-to-noise ratio across different luminance levels becomes suboptimal
Solution Approach 1:
The patent determines a scaling parameter for each block individually and applies it locally within the coding loop. This local processing approach allows each block to be optimized for its specific luminance characteristics and signal-to-noise ratio distribution, improving both compression efficiency and perceptual quality simultaneously by adapting to local variations in the video content.
Data Source
AI summary
A device for decoding video data receives the video data, determines a scaling parameter for a block of the video data; and scales the block in a video decoding loop using the scaling parameter to increase a dynamic range for luminance values of the block. A device for encoding video data partitions the video data into blocks; determines a scaling parameter for a block of the video data; and scales the block in a video encoding loop using the scaling parameter to decrease a dynamic range for luminance values of the block.