Stray Light Compensation Using Dual Imaging Devices
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Solution Overview
Problem
Stray light, or lens flare, in digital camera images reduces contrast and color saturation, limiting the dynamic range and signal-to-noise ratio, especially due to bright light sources outside the camera's field-of-view.
Innovation Solution
A method involving a first and second imaging device, where the second device captures a larger field-of-view image with lower exposure to estimate and subtract stray light components from the first image, using gaussian filters and compensating for exposure and gain differences, thereby improving the signal-to-noise ratio and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single imaging device captures an image with a limited field-of-view, then the image quality in terms of contrast and color saturation is degraded by stray light from outside the field-of-view, but using a larger field-of-view imaging device would capture more stray light components
Solution Approach 1:
The patent divides the imaging task into two separate imaging devices: a first imaging device with a smaller field-of-view for capturing the primary image, and a second imaging device with a larger field-of-view for capturing stray light components. This segmentation allows each device to be optimized for its specific function, resolving the contradiction between limiting field-of-view to reduce stray light and needing a wider field to capture all stray light components for compensation.
Solution Approach 2:
The second imaging device acts as an intermediary that captures stray light information from a wider field-of-view. This intermediary device provides the stray light data that is then used to compensate for stray light effects in the first image, allowing the system to benefit from both limited and extended field-of-view approaches.
2Measurement precision
If the second imaging device uses lower exposure to capture stray light components, then the stray light estimation is improved, but the signal-to-noise ratio in the second image decreases
Solution Approach 1:
The patent applies different exposure settings to different imaging devices based on their specific functions. The second imaging device uses lower exposure specifically optimized for capturing stray light components without saturation, while the first imaging device uses normal exposure for the primary image. This local optimization of exposure parameters allows accurate stray light estimation while maintaining adequate signal-to-noise ratio for the compensation process.
3Reliability
If multiple imaging devices with different fields-of-view are used for stray light compensation, then the dynamic range and signal-to-noise ratio in the final image are improved, but the device complexity increases
Solution Approach 1:
The patent merges the outputs of two imaging devices through a computational process that combines the primary image from the first device with the stray light compensation data from the second device. This merging of data streams achieves improved dynamic range and signal-to-noise ratio while keeping the hardware complexity manageable through software-based integration.
Solution Approach 2:
The system achieves multi-functionality by using the second imaging device not only for stray light compensation but also potentially for other wide-angle imaging tasks. The dual-imaging-device setup serves multiple purposes: primary image capture, stray light measurement, and potentially environmental monitoring, thereby justifying the increased device complexity through enhanced versatility.
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
The method effectively compensates for stray light, enhancing image quality by reducing noise and improving detail representation in darker areas, even when not perfectly calibrated.
Implementation Method 1
light is scattered by the lens arrangement itself, for example through internal reflection and forward scattered from material imperfections in lenses of the lens arrangement
Implementation Method 2
filtering the second image by a series of gaussian filters forming a series of filtered second images
Data Source
AI summary
A method for stray light compensation is disclosed. The method comprising: acquiring a first image with a first imaging device covering a first field-of-view; acquiring a second image with a second imaging device covering a second field-of-view, wherein the second field-of-view is larger than the first field-of-view and wherein the first field-of-view is included in the second field-of-view; estimating stray light components in pixels of the first image from pixel data of pixels in the second image; and compensating for stray light in the first image by subtracting the estimated stray light components in pixels of the first image. Also, a system for stray light compensation is disclosed.