Gain Map Embedding for Consistent HDR Display Adaptation
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Solution Overview
Problem
Conventional high dynamic range (HDR) techniques for digital images lack consistency across different display devices and environmental conditions, leading to reduced display functionality, diminished contrast, and inaccuracies due to variations in HDR capabilities and environmental factors.
Innovation Solution
A gain map is generated and embedded within a digital image file, allowing for dynamic adjustment of luminosity values between standard dynamic range (SDR) and HDR, along with metadata that defines how the gain map is applied, enabling consistent HDR functionality across various devices and platforms while supporting backward compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HDR techniques are used, then HDR functionality is supported, but consistency across different display devices and environmental conditions deteriorates
Solution Approach 1:
The patent segments the HDR implementation into distinct components: a base SDR image, a gain map containing luminosity adjustment data, and metadata describing application parameters. This segmentation allows each component to be independently optimized and applied based on device capabilities, ensuring consistency across different display devices while maintaining adaptability.
Solution Approach 2:
The patent changes the parameter representation by using a gain map that stores luminosity ratios rather than absolute HDR values. The gain map contains per-pixel or per-region gain factors that can be applied multiplicatively to the base image, allowing dynamic adaptation to different display characteristics and environmental conditions through metadata-driven parameter adjustment.
2Manufacturing precision
If HDR processing is performed without a gain map, then processing speed is maintained, but luminosity control precision and display quality deteriorate
Solution Approach 1:
The patent performs preliminary action by pre-calculating the gain map from the HDR image during the image creation phase. This gain map captures the luminosity relationships in advance, allowing fast application during display without requiring complex real-time HDR processing. The metadata also prepares application parameters beforehand, enabling efficient runtime processing while maintaining high luminosity control precision.
3Reliability
If separate SDR and HDR images are stored, then image quality is maintained, but data storage efficiency deteriorates
Solution Approach 1:
The patent merges the SDR and HDR information into a single compact representation by storing only the base SDR image and a gain map that encodes the luminosity adjustments. Instead of storing two full-resolution images, the gain map uses compressed representations (such as lower resolution, quantized values, or transform-domain encoding) to represent the differences, significantly reducing storage requirements while maintaining the ability to reconstruct both SDR and HDR versions.
4Adaptability or versatility
If gain map is applied dynamically, then adaptability to different devices is improved, but processing time and computational resources increase
Solution Approach 1:
The patent applies local quality by allowing different regions of the image to have different gain map resolutions and compression levels. Important regions (such as high-contrast areas or focal points) can be represented with higher precision, while less critical regions use coarser representations. This selective approach reduces overall processing time and computational resources while maintaining adaptability to different display devices where local quality requirements may vary.
Data Source
AI summary
Gain map generation, embedding, and application for high dynamic range digital image functionality are described. In one example, a gain map is generated based on a digital image, e.g., as a ratio of a standard dynamic range digital image and a high dynamic range digital image. The gain map is configured to adjust an amount of gain of a digital image between a high dynamic range (HDR) and a standard dynamic range (SDR). Metadata is generated based on the gain map. The metadata describes how the gain map is to be applied to the digital image as part of rendering. The gain map, the metadata, and the digital image are embedded within a digital image file and stored.