Dynamic HDR Contrast Adaptation Across SDR Display Ranges
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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 compromising image quality.
Innovation Solution
A method and apparatus for adapting HDR video pixel luminances using a luminance mapping function to convert HDR images to SDR images, utilizing metadata to communicate the mapping function, allowing displays to adjust pixel luminances based on their capabilities, ensuring optimal image quality across varying display luminance ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HDR video is converted to SDR using conventional luminance mapping, then compatibility with standard displays is improved, but image quality deteriorates due to loss of luminance detail
Solution Approach 1:
The patent applies dynamic tone mapping that adapts the luminance mapping function based on the specific HDR content characteristics and target display capabilities. Instead of using a fixed mapping function, the system dynamically adjusts the mapping parameters to preserve luminance relationships in the converted SDR image, thereby maintaining image quality while ensuring display compatibility.
Solution Approach 2:
The patent changes the luminance mapping parameters based on the HDR video content and target display characteristics. By adjusting the mapping function parameters dynamically rather than using a static mapping, the system preserves more luminance detail during conversion from HDR to SDR, thus improving image quality while maintaining compatibility.
2Manufacturing precision
If multiple image formats are maintained for different display capabilities, then image quality for each display type is optimized, but data transmission complexity increases
Solution Approach 1:
The patent creates a universal HDR image format that can be efficiently converted to suit different display capabilities. Instead of maintaining separate optimized formats for HDR and SDR displays, the system uses a single HDR source that can be adaptively converted to various output formats, thereby reducing data transmission complexity while maintaining image quality for different display types.
Solution Approach 2:
The patent performs preliminary encoding in HDR format with embedded metadata that contains information about the original luminance characteristics. This preliminary action allows the conversion to SDR to be performed efficiently at the display end without requiring multiple pre-encoded versions, thus reducing transmission complexity while preserving image quality.
Data Source
AI summary
Obtaining improved watchable images for various viewing environment light levels by processing an input image to obtain an output image. The input image has input luminances which fall within a first luminance dynamic range and a maximum luminance. The reference luminance mapping metadata associated with the input image. An adapted luminance mapping function is based on the reference luminance mapping function. The adapted luminance mapping function is applied to the input pixel luminances, to obtain output luminances of the output image.