Head-Mounted Passthrough Dimming for Low-Light Noise Masking
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Solution Overview
Problem
Head-mounted devices struggle to display high-quality images in various usage contexts, particularly in dark environments where captured video feeds appear noisy, degrading the viewing experience due to low signal-to-noise ratio.
Innovation Solution
Implement a brightness scaling subsystem that adjusts display brightness based on scene brightness levels, using tone-mapping algorithms to mask noise in passthrough content and control virtual content brightness, ensuring a clear image presentation even in low-light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the video feed of a dark environment is displayed with high brightness to improve visibility, then the viewing experience is enhanced, but the noise in the image becomes more apparent and degrades quality
Solution Approach 1:
The patent applies parameter changes by implementing a non-linear brightness mapping function that transforms scene brightness to display brightness. When scene brightness is below a threshold, the mapping function reduces display brightness more aggressively than linear scaling, which suppresses noise visibility while maintaining acceptable image quality. This resolves the contradiction by dynamically adjusting the brightness parameter based on scene conditions rather than using fixed high brightness.
2Object-affected harmful factors
If the display brightness is reduced to mask noise in dark scenes, then image quality improves, but overall visibility and viewing experience deteriorates
Solution Approach 1:
The patent implements dynamics by using adaptive brightness mapping that responds to scene brightness levels. The system dynamically selects between different mapping strategies: for bright scenes, it uses near-linear mapping to preserve visibility, while for dark scenes below a threshold, it transitions to aggressive dimming to mask noise. This dynamic adaptation resolves the contradiction by adjusting brightness based on real-time scene conditions rather than applying a static reduction.
Solution Approach 2:
The patent applies local quality by implementing different brightness mapping characteristics for different scene brightness ranges. Rather than applying uniform brightness reduction across all scenes, the system uses a piecewise mapping function that applies aggressive dimming only in the low-brightness region where noise is problematic, while preserving near-linear mapping in brighter regions where visibility is the priority. This localized approach resolves the contradiction by applying noise masking only where necessary.
3Measurement precision
If a 1:1 nits-to-nits brightness mapping is used to preserve scene accuracy, then fidelity to the original scene is maintained, but noise in dark environments becomes more visible
Solution Approach 1:
The patent resolves this contradiction by making the brightness mapping dynamic rather than static. The system implements a scene-brightness-to-display-brightness profile that adapts based on the measured scene brightness level. When scene brightness exceeds a threshold, the system maintains near-1:1 mapping for fidelity. When scene brightness falls below the threshold, the system transitions to aggressive dimming with a slope less than one, which masks noise while accepting some deviation from perfect fidelity. This dynamic switching resolves the contradiction between fidelity and noise suppression.
Data Source
AI summary
A method of operating an electronic device to mask noise at low scene brightness levels is provided. The method can include acquiring images of a scene and determining a scene brightness level of the acquired images. In response to determining that the scene brightness level is in a first range, the acquired images can be displayed as passthrough content in accordance with a 1:1 nits-to-nits mapping where the perceived brightness of the passthrough content matches the scene brightness level. In response to determining that the scene brightness is less than the first range, the perceived brightness of the passthrough content can be dimmed to be less than the scene brightness level. The method can also include generating virtual content. The passthrough content can be adjusted in accordance with a first scene-brightness-to-display-brightness profile, whereas the virtual content can be adjusted in accordance with a second scene-brightness-to-display-brightness profile.