Gain Map Block Encoding for HDR Storage and Image Quality
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Solution Overview
Problem
High-dynamic-range (HDR) images require gain maps for display on both HDR and standard-dynamic-range (SDR) devices, but existing methods of storing and encoding gain maps increase storage space and affect image quality due to information loss during downsampling.
Innovation Solution
A method and apparatus for encoding and decoding gain maps by identifying and encoding target image blocks with luminance values above a threshold, using block identification information and adaptive resolution to reduce data retention while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If gain map is stored by performing downsampling and then compressing and encoding, then storage space is reduced, but information is lost and image quality is affected
Solution Approach 1:
The gain map is divided into multiple image blocks, and each block is processed independently. Blocks with luminance values above a threshold are identified as target blocks and encoded separately from non-target blocks, allowing selective compression that preserves important information while reducing storage space for less critical regions.
Solution Approach 2:
Different regions of the gain map are treated differently based on their luminance characteristics. Target image blocks with higher luminance values receive different encoding treatment compared to non-target blocks, optimizing the balance between storage efficiency and image quality preservation for each region.
2Quantity of substance
If gain map is stored by performing downsampling and then compressing and encoding, then storage space is reduced, but image quality of reconstructed image is affected
Solution Approach 1:
The gain map is segmented into multiple image blocks, with target blocks (luminance > threshold) and non-target blocks processed separately. This segmentation allows selective downsampling and compression, preserving quality in important high-luminance regions while reducing storage for less critical areas.
Solution Approach 2:
The encoding process uses variable parameters based on block characteristics. Target image blocks use one set of encoding parameters optimized for quality preservation, while non-target blocks use different parameters optimized for compression, achieving overall storage efficiency without sacrificing critical image quality.
Data Source
AI summary
A gain map encoding method and apparatus, a gain map decoding method and apparatus, a device, and a medium. The method in this application includes: obtaining at least one target image block in a gain map, where a luminance value of a pixel in the target image block is greater than a first threshold; determining target image block identification information of the gain map and an image block group based on the at least one target image block; and encoding the target image block identification information and the image block group to obtain encoding information of the gain map.