Dynamic Exposure Ratio Control for HDR Imaging Noise Reduction
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Solution Overview
Problem
Existing imaging technologies face challenges in generating images with expanded dynamic range due to noise issues, particularly false colors and pseudo contours, when combining images taken at different exposures, as they often fail to dynamically determine optimal exposure ratios for multi-stage exposure settings.
Innovation Solution
An imaging device and method that dynamically adjusts exposure ratios between adjacent exposure stages to ensure equal ratios, allowing for the combination of pixel signals with minimal noise by setting exposure times such that the ratios of adjacent exposures are equal, thereby maintaining consistent brightness across dark and bright sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If images are combined from multiple exposure stages with fixed exposure ratios, then dynamic range is expanded, but noise artifacts (false colors and pseudo contours) occur in boundary areas
Solution Approach 1:
The patent implements dynamic adjustment of exposure ratios between multiple imaging stages based on real-time detection of subject brightness distribution. The control unit calculates the brightness distribution of the subject and dynamically determines optimal exposure ratios for each stage, replacing fixed predetermined ratios. This dynamic adaptation ensures that exposure transitions between stages are optimized for each specific scene, minimizing noise artifacts in boundary areas while maintaining expanded dynamic range.
Solution Approach 2:
The patent changes the exposure ratio parameter dynamically based on subject characteristics. By detecting the brightness distribution of the subject and calculating optimal exposure ratios, the system adjusts the exposure parameters for each imaging stage. This parameter optimization ensures that the transition between different exposure levels is smooth and appropriate for the specific scene, reducing noise artifacts while preserving the benefits of multi-exposure dynamic range expansion.
2Adaptability or versatility
If exposure ratios between adjacent stages are not equal, then imaging flexibility is maintained, but linearity of combined image signal is distorted
Solution Approach 1:
The patent implements a feedback mechanism where the control unit detects the brightness distribution of the subject and uses this information to determine optimal exposure ratios. The system continuously monitors scene characteristics and adjusts exposure ratios accordingly, ensuring that the feedback loop maintains both signal linearity and imaging flexibility. This feedback-driven approach allows the system to adapt to different scene conditions while preserving accurate signal relationships for high-quality HDR combination.
3Device complexity
If fixed exposure ratios are used in multi-stage exposure, then device complexity is reduced, but noise components increase due to S/N limitations
Solution Approach 1:
The patent enables the imaging system to automatically determine optimal exposure ratios through self-service mechanisms. The control unit autonomously detects subject brightness distribution and calculates the best exposure ratios without requiring complex external intervention or manual configuration. This self-service approach allows the system to optimize noise performance adaptively while maintaining relatively simple device architecture, as the optimization is performed automatically based on scene characteristics.
Data Source
AI summary
An imaging device includes: an imaging unit that images a subject with three or more kinds of exposures, ratios of respective pairs of exposures of which adjacent to each other in an ascending order or a descending order are equal; and a combining unit that combines, on the basis of the ratios, pixel signals corresponding to the respective three or more kinds of exposures obtained by imaging the subject with the imaging unit.