HDR Video Luminance Mapping for Adaptive Display Contrast
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Solution Overview
Problem
Existing HDR video coding technologies struggle to optimally adapt image pixel luminances for different display capabilities, particularly when transitioning from high dynamic range (HDR) to standard dynamic range (SDR), without considering the impact of ambient lighting and minimum displayable luminance.
Innovation Solution
A method and apparatus for adapting HDR video pixel luminances using a luminance mapping function to convert between HDR and SDR formats, incorporating display adaptation algorithms that consider both maximum and minimum luminance capabilities of the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HDR video is converted to SDR using traditional luminance mapping, then compatibility with standard displays is improved, but image quality and contrast are degraded
Solution Approach 1:
The patent applies tone mapping before luminance mapping to pre-process the HDR image data. This preliminary action preserves luminance relationships and contrast information before the conversion to SDR, preventing the quality loss that occurs when mapping is applied directly to raw HDR data.
Solution Approach 2:
The patent introduces an intermediate processed image as a mediator between the original HDR image and the final SDR output. This intermediate representation maintains the luminance structure of HDR while being prepared for SDR conversion, allowing quality preservation during the transition.
2Illumination intensity
If maximum luminance is increased for HDR displays, then dynamic range is improved, but adaptability to different viewing environments is worsened
Solution Approach 1:
The patent implements dynamic adaptation by allowing the luminance mapping parameters to change based on detected ambient lighting conditions. The system dynamically adjusts the mapping function to optimize image appearance for the current viewing environment while maintaining HDR quality on capable displays.
Solution Approach 2:
The patent changes the luminance mapping parameters based on ambient light detection. By adjusting mapping parameters rather than fixed conversion, the system adapts to different viewing conditions (bright, dim, HDR-capable) while preserving image quality and contrast across environments.
3Device complexity
If simple luminance mapping is used for HDR to SDR conversion, then processing complexity is reduced, but contrast and image fidelity are lost
Solution Approach 1:
The patent applies tone mapping as a preliminary processing step before luminance mapping. This pre-processing organizes the luminance data in a way that preserves contrast relationships, allowing subsequent mapping to maintain fidelity without requiring excessively complex processing.
Data Source
AI summary
The invention creates improved images for various viewing environment light levels. The invention process an input image with an input luminance dynamic range with an input maximum luminance using a processing system. The input image has metadata which specifies a reference luminance mapping function. The output image has an adjusted maximum luminance determined by subtracting a user correction value from an output maximum luminance. The luminances of the input image are processed using an adapted luminance mapping function. The adapted luminance mapping function is based on the adjusted maximum luminance value and the reference luminance mapping function.