High Dynamic Range Exposure Control for SNR Transition Artifacts
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Solution Overview
Problem
In multi-exposure imaging, abrupt signal-to-noise ratio (SNR) transitions between similar tones degrade image quality and introduce undesirable artifacts due to merging images with different SNR profiles, which existing methods have not adequately addressed.
Innovation Solution
A system and method that utilize a controller to capture multiple exposures with varying exposure times, adjusting integration ratios to achieve a desired minimum SNR across the tonal range by partitioning the ratio between exposure segments and adjusting exposure times to control SNR, thereby optimizing image quality and minimizing motion artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple exposures with different exposure times are merged to capture high dynamic range, then the dynamic range is improved, but abrupt SNR transitions and artifacts are introduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting exposure times and integration ratios for different exposures. Specifically, it modifies the exposure parameters (exposure time, integration ratio) based on scene luminance characteristics to ensure that merged exposures maintain consistent SNR profiles, thereby resolving the SNR transition problem while preserving high dynamic range capability
Solution Approach 2:
The patent implements dynamics by making the exposure sequence adaptive rather than fixed. It dynamically determines exposure times and integration ratios based on real-time scene analysis and luminance histograms, allowing the system to optimize SNR consistency across different lighting conditions while maintaining high dynamic range performance
2Reliability
If exposure time is increased to improve SNR, then noise is reduced, but motion artifacts increase
Solution Approach 1:
The patent applies local quality by treating different regions of the image with different exposure strategies. It analyzes luminance histograms to identify dark regions that benefit from longer exposures and separates their processing from brighter regions, applying appropriate integration ratios locally to maintain SNR without introducing motion artifacts in regions where short exposures are sufficient
Solution Approach 2:
The patent segments the exposure process into multiple controlled integrations with different exposure times and integration ratios. By dividing the total exposure into discrete segments (first integration, second integration, etc.) with optimized parameters, it achieves high SNR in dark regions while limiting motion artifact accumulation through controlled segment durations
Data Source
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AI summary
Method and apparatus for controlling signal-to-noise ratio (SNR) in high dynamic range automatic exposure control imaging are disclosed. In the method and apparatus, image data is received and a shadow threshold is determined based on the image data. Further, a respective threshold integration ratio is determined for each merge transition of a plurality of exposures having a respective plurality of exposure times. The threshold integration ratio is determined based on a threshold SNR for the merge transition. In the method and apparatus, an integration ratio for each merge transition is determined based on the shadow threshold and the threshold integration ratios. An output image is generated based on the determined integration ratios for each merge transition.