Image Range Expansion Control for High Peak Luminance Displays
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Solution Overview
Problem
High-performance displays with advanced capabilities such as high peak luminance and broad color gamuts pose challenges in adjusting images without introducing noticeable artifacts like banding, quantization artifacts, and film grain when displaying content optimized for lower luminance or gamut displays.
Innovation Solution
A method and apparatus that process image data by determining a maximum safe expansion based on metadata and the target display's capabilities, expanding the dynamic range and color gamut to match the target display's capabilities while avoiding artifacts, using a tone mapping curve and expansion functions to adjust image data for optimal viewing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the luminance range of image data is expanded to take advantage of high peak luminance of target display, then the display capability is improved, but artifacts such as banding and quantization artifacts become apparent
Solution Approach 1:
The patent applies parameter changes by modifying the luminance range of image data through controlled expansion. The system adjusts the luminance parameters to match the target display's capabilities while applying tone mapping curves to prevent artifacts. This involves changing the distribution of luminance values to optimize for high peak luminance displays without introducing visible banding or quantization artifacts.
2Object-affected harmful factors
If the image is displayed on target display without range expansion, then artifacts are avoided, but no benefit is gained from high peak luminance capability
Solution Approach 1:
The patent applies partial action by performing selective luminance range expansion only where beneficial and safe. Rather than expanding the full luminance range, the system performs partial expansion up to a maximum safe level determined by analyzing the source image characteristics and target display capabilities. This partial expansion approach captures benefits of high peak luminance while avoiding the threshold where artifacts become visible.
3Manufacturing precision
If tone mapping curve is applied to expand dynamic range, then image quality is improved, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing tone mapping curves for different display characteristics. The system prepares transformation curves in advance based on target display capabilities and source image analysis, then applies these pre-computed curves during display. This preliminary preparation reduces real-time processing complexity while maintaining high image quality through sophisticated tone mapping.
Data Source
AI summary
Image data is adjusted for display on a target display. Maximum safe expansions for one or more attributes of the image data are compared to maximum available expansions for the attributes. An amount of expansion is selected that does not exceed either of the maximum safe expansion and the maximum available expansion. Artifacts caused by over expansion may be reduced or avoided.