Selective Gamma Band Adjustment for HMD Contrast
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Solution Overview
Problem
Head-mounted display devices for virtual reality suffer from a low contrast ratio, leading to visual fatigue and distraction due to the 'screen-door' effect, where users can see spaces between pixels.
Innovation Solution
Implementing selective gamma correction with multiple gamma bands to adjust pixel luminance, allowing for improved contrast ratio by making dark areas darker and light areas lighter, thereby mitigating the low contrast issue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional display technology is used in HMD, then device complexity is low, but contrast ratio is poor causing screen-door effect
Solution Approach 1:
The patent applies parameter changes by implementing multiple gamma bands (first gamma band with first gamma value, second gamma band with second gamma value) to adjust the luminance characteristics of different pixel regions. This changes the display parameters dynamically based on spatial position, improving contrast ratio without requiring fundamental changes to the display hardware architecture.
Solution Approach 2:
The patent implements local quality by applying different gamma correction parameters to different spatial regions of the display. Pixels in first regions use first gamma values while pixels in second regions use second gamma values, creating locally optimized contrast characteristics that address the screen-door effect in specific areas without affecting the entire display uniformly.
2Illumination intensity
If pixel luminance is increased to improve visibility, then brightness is improved, but contrast ratio deteriorates due to screen-door effect
Solution Approach 1:
The patent changes the gamma parameter values spatially across the display to simultaneously optimize brightness and contrast ratio. By using different gamma values in different regions, the system can enhance brightness where needed while maintaining high contrast ratio in critical viewing areas, resolving the trade-off between these two parameters.
Data Source
AI summary
A virtual-reality device includes a data generator, one or more processors, two or more gamma bands, and a display. The virtual-reality device generates initial color values for each of the plurality of pixels, and determines a respective gray-level value for each of the pixels according to the generated color values. The device selects, for each of the pixels, a respective gamma band corresponding to the determined respective gray-level value and one or more respective contextual markers, where each gamma band has a distinct luminance target. The virtual-reality device then adjusts the luminance level of each pixel according to the respective selected gamma band and displays the pixels according to the adjusted luminance levels.