Dynamic Luminance Threshold for HDR Highlight Alarm Detection
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Solution Overview
Problem
Conventional HDR image processing techniques struggle to provide appropriate highlight alarm indications due to varying maximum luminance output depending on gamma curve shape, making it difficult to detect regions that will become blown-out highlights effectively.
Innovation Solution
An image processing apparatus and method that acquires an HDR signal, detects regions for highlight alarm indications by applying a threshold based on the possible maximum value of the HDR signal, and provides a highlight alarm indication, ensuring recognition of high-luminance regions in HDR images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed threshold method (zebra indication) is used to detect highlight regions, then the detection is simple and fast, but the detection accuracy deteriorates because maximum luminance varies depending on gamma curve shape in HDR standards
Solution Approach 1:
The patent applies dynamics by making the threshold dynamic rather than fixed. The threshold is calculated based on the actual maximum luminance value detected in the HDR image and the specific gamma curve being used. This allows the threshold to adapt to different gamma curves (PQ, HLG, etc.) and different maximum luminance values, resolving the contradiction between simple fixed-threshold detection and accurate adaptive detection.
Solution Approach 2:
The patent changes the parameter of the threshold from a fixed value to a calculated value that depends on the gamma curve characteristics and maximum luminance. By modifying this key parameter, the system achieves accurate highlight detection across different HDR standards while maintaining computational efficiency through formula-based calculation rather than complex analysis.
2Illumination intensity
If HDR display maximum luminance is increased to improve highlight representation, then the luminance dynamic range is enhanced, but the risk of blown-out highlights increases making them harder to recognize
Solution Approach 1:
The patent implements feedback by providing a visual indication (highlight alarm) that feeds back to the user about regions approaching maximum luminance. This allows users to adjust exposure or other parameters before blown-out highlights occur, creating a closed-loop system that prevents the harmful effect while allowing high maximum luminance display capability.
Solution Approach 2:
The patent applies preliminary action by detecting and indicating highlight regions before they become completely blown-out. By showing the alarm indication in advance, the system allows preventive action to be taken, resolving the contradiction between displaying high luminance and preventing loss of highlight detail.
Data Source
AI summary
An image processing apparatus acquires a high dynamic range (HDR) signal generated in compliance with an HDR standard, detects a region for which a highlight alarm indication is to be provided, by applying a threshold to the HDR signal, and provides a highlight alarm indication for the detected region. The HDR standard is a standard in which luminance values are handled as absolute values, and the region is detected by applying a threshold that is based on a possible maximum value of the HDR signal.