Monochromatic Sensor Dual Exposure Dynamic Range
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Solution Overview
Problem
Current digital camera systems, particularly in endoscopic applications, face limitations in dynamic range, leading to loss of details in low-light areas due to insufficient ability to capture broad luminosity ranges without compromising bright area information.
Innovation Solution
The implementation of a dual exposure method using a checkerboard pattern of short and long exposure pixels, synchronized with pulsed monochromatic light sources, allows for enhanced dynamic range by alternating pixel configurations frame by frame, and sharing transistors between neighboring pixels to reduce noise and increase quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single exposure time is used for all pixels, then the device complexity is low and the operation is simple, but the dynamic range is limited and details in low-light areas are lost
Solution Approach 1:
The image sensor array is segmented into two distinct groups of pixels: first pixels with a first exposure time and second pixels with a second exposure time. This segmentation allows different regions of the sensor to capture different exposure ranges simultaneously, enabling the system to preserve details in both bright and low-light areas without requiring complex post-processing or multiple captures
Solution Approach 2:
The system dynamically alternates between two exposure configurations across successive image frames. In odd frames, first pixels capture with the first exposure time while second pixels capture with the second exposure time. In even frames, the roles are reversed. This dynamic switching allows the system to adapt to varying luminosity conditions while maintaining a relatively simple hardware architecture
2Illumination intensity
If longer exposure time is used to capture low-light areas, then the dynamic range increases, but the bright area information is compromised due to saturation
Solution Approach 1:
The sensor array is divided into pixels with different exposure times, where first pixels use a shorter exposure time optimized for bright areas and second pixels use a longer exposure time optimized for low-light areas. This spatial segmentation of exposure characteristics allows simultaneous capture of both bright and dark regions without cross-contamination or information loss
Solution Approach 2:
Different regions of the sensor array are assigned different exposure qualities tailored to their specific capture needs. First pixels are configured with exposure parameters suited for brighter regions, while second pixels are configured with exposure parameters suited for darker regions. This local optimization of exposure characteristics ensures that each pixel captures information within its optimal dynamic range
3Loss of information
If multiple pixel types with different exposures are used, then the dynamic range is extended, but the spatial resolution may be reduced
Solution Approach 1:
The system merges data from two different exposure configurations by capturing alternating frames with swapped pixel roles. For each pixel location, information from both the shorter and longer exposure captures is combined, effectively creating a high dynamic range image at full spatial resolution. This merging approach preserves the full spatial resolution of the sensor array while achieving extended dynamic range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively extends the dynamic range, enabling the capture of detailed images across a broader luminosity range without sacrificing spatial resolution or introducing significant noise, thereby improving the overall image quality in low-light conditions.
Implementation Method 1
synchronized with pulsed monochromatic light sources
Implementation Method 2
checkerboard pattern of short and long exposure pixels
Data Source
AI summary
The disclosure extends to methods, systems, and computer program products for widening dynamic range within an image in a light deficient environment.