Target-less Turbid Media Calibration via Backscatter Analysis
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Solution Overview
Problem
Current methods for calibrating color images in turbid media, such as underwater environments, require external hardware or cumbersome calibration targets, and struggle with estimating medium properties like attenuation and scattering, which complicates 3D scene reconstruction and color consistency.
Innovation Solution
A method that uses backscattered light from two or more images with varying light source locations to compute attenuation and scattering coefficients, allowing for color correction without external calibration targets, using the camera's inherent optical properties and processing hardware to reconstruct color-consistent images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external calibration targets or hardware are used to estimate attenuation parameters, then measurement precision is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The system uses the imaging device itself to perform calibration by capturing images of the scene at different exposure settings, eliminating the need for external calibration targets or hardware. The calibration process is self-contained within the imaging device's existing components.
Solution Approach 2:
The patent introduces an intermediary processing step that uses image difference analysis between multiple exposures to extract attenuation information without requiring external calibration objects. This intermediary method bridges the gap between raw images and accurate attenuation parameters.
2Measurement precision
If multiple images of an object at different distances are used to estimate attenuation, then measurement precision improves, but loss of time and productivity worsen
Solution Approach 1:
The system performs preliminary calibration by capturing multiple images at different exposure settings before final processing. This preliminary action of capturing varied exposure images enables subsequent efficient computation of attenuation parameters without requiring time-consuming physical repositioning or additional calibration steps.
Solution Approach 2:
The patent uses a simplified approach that only requires image difference analysis from a limited set of exposures rather than comprehensive multi-distance imaging. This partial action approach achieves sufficient precision while significantly reducing time requirements.
3Measurement precision
If backscatter is removed by working beyond saturation distance, then measurement precision improves, but loss of energy and signal-to-noise-ratio worsen
Solution Approach 1:
The patent converts the harmful backscatter effect into a useful signal by using it as part of the calibration process. Instead of trying to eliminate backscatter by working at saturation distances, the method uses backscatter present in images at various exposures to compute attenuation parameters, thereby maintaining signal-to-noise-ratio while achieving accurate measurements.
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
Enables reliable color information recovery in turbid media, improving color consistency and reducing noise, especially in high-turbidity conditions, without the need for additional hardware, thus facilitating applications like scientific research and environmental monitoring.
Implementation Method 1
A method that uses backscattered light from two or more images with varying light source locations to compute attenuation and scattering coefficients
Data Source
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Figure 3A~3C
Figure 4A~4B
AI summary
A method comprising acquiring a first image of a scene inside a medium, under illumination from a first location or orientation. The method comprises an action of acquiring a second image of the scene inside the medium, under illumination from a second, different location or orientation. The method comprises an action of computing attenuation coefficients, one per color channel, based on backscatter in the first and second images.