Luminance Sample Determination for HDR Chroma Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current video encoding and decoding technologies face challenges in efficiently processing high-dynamic range (HDR) video, particularly in maintaining computational efficiency and reducing color banding, due to the high computational complexity of HDR reconstruction and the need for simultaneous use of HEVC capabilities like color spacing and scalable coding extensions.
Innovation Solution
The method involves determining a luminance value for processing color samples in a decoder or encoder, primarily performing HDR decoding and encoding in the 4:2:0 chroma format with 10-bit integer samples, and using synchronous chroma down-sampling to minimize computational complexity and optimize HDR compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HDR reconstruction is performed using conventional methods with multiple processing steps, then video quality is improved, but computational complexity increases significantly
Solution Approach 1:
The patent extracts and removes unnecessary intermediate processing steps from the conventional HDR reconstruction workflow. By eliminating redundant color space conversions and processing stages, the solution maintains video quality while significantly reducing computational complexity and processing time.
Solution Approach 2:
The patent performs preliminary color space conversion and luminance determination during the encoding phase rather than during decoding. By preparing and storing pre-computed color transformation matrices and luminance values in advance, the decoding process requires minimal computation, thus reducing device complexity while preserving video quality.
2Productivity
If color sampling is performed in 4:2:0 format to reduce data rate, then compression efficiency is improved, but color accuracy and HDR reconstruction quality deteriorate
Solution Approach 1:
The patent introduces an intermediary luminance determination step that operates on the down-sampled 4:2:0 chroma samples. By calculating luminance values from the chroma components using pre-computed matrices, the system recovers accurate color information without requiring full-resolution chroma samples, thus maintaining both compression efficiency and color accuracy.
Solution Approach 2:
The patent transforms the color sampling approach by changing the parameter representation from direct chroma values to luminance-derived values. By converting chroma samples to luminance space and back using optimized transformations, the system achieves accurate HDR reconstruction from 4:2:0 data, preserving color accuracy while maintaining compression efficiency.
3Productivity
If multiple HEVC capabilities are used simultaneously, then coding efficiency is improved, but implementation complexity and compatibility issues arise
Solution Approach 1:
The patent merges multiple HEVC capabilities (color spacing, scalable coding extensions, and HDR reconstruction) into a unified processing framework. By integrating these separate functions into a single coherent workflow with shared data structures and processing paths, the system achieves high coding efficiency while reducing implementation complexity and improving decoder compatibility.
Data Source
AI summary
A method for determining a luminance value used to process color samples in a decoder or encoder is provided comprising determining (33, 44) a luminance sample associated with a chroma sample position in a common space; and applying (34, 492) the determined luminance sample in a process that depends on luminance that is being applied to the chroma sample.