Color Filter Optimization for Vision System Spectral Response
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Solution Overview
Problem
Digital cameras struggle to accurately capture colors as they do not meet the Luther condition, resulting in low sensitivity and high noise levels, and existing color correction methods fail to deliver optimal colorimetric performance, especially for saturated colors.
Innovation Solution
A method and system for generating a color filter that modifies the spectral response of a vision system by using a bilinear optimization problem to determine a color correction matrix and filter parameters, ensuring a bounded total transmittance and average light power transmission, thereby improving color accuracy and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter is placed in front of a camera to improve colorimetric performance, then color accuracy is improved, but light transmission is reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the filter's spectral transmittance function T(λ) to achieve the best colorimetric performance while maintaining adequate light transmission. The bilinear optimization adjusts the filter parameters to satisfy both the Luther condition for color accuracy and transmittance constraints for light transmission.
Solution Approach 2:
The patent changes the camera's spectral sensitivity parameters by multiplying the original sensitivities S(λ) by the filter transmittance T(λ) to create new effective sensitivities S'(λ) = S(λ) × T(λ), which satisfy the Luther condition while preserving as much light as possible.
2Measurement precision
If exposure time is increased to compensate for filter-induced light loss, then color accuracy is maintained, but noise increases
Solution Approach 1:
The patent converts the harmful effect of light loss into a benefit by designing a filter that selectively transmits wavelengths important for color accuracy while blocking others, achieving better colorimetric performance without requiring excessive exposure time increases that would amplify noise.
3Ease of operation
If a simple 3×3 matrix is used for color correction, then the processing is simple, but colorimetric accuracy is insufficient especially for saturated colors
Solution Approach 1:
The patent applies preliminary action by placing a color filter in front of the camera sensor before light detection, which pre-corrects the spectral response to satisfy the Luther condition. This preliminary optical correction enables subsequent simple linear color transformation to achieve accurate colorimetric results, including for saturated colors.
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 approach results in a 10% improvement in color accuracy while meeting transmittance requirements, producing filters that allow cameras to capture colors more accurately, with higher light transmission and reduced noise, making them more colorimetric.
Implementation Method 1
a filter is placed in front of a first vision system so that its filter corrected responses are closer to those of a second vision system
Data Source
AI summary
A system and method for generating an improved color filter for modifying the spectral response of a vision system are disclosed. the method includes receiving an RGB spectral response of the vision system for a color target under predetermined illumination, generating a model, using the RGB spectral response, of the vision system when subject to a filter, the model including a bounded total transmittance of light by the filter that is set by a predetermined parameter and executing, by a processor of a computer system, computer program instructions configured to apply the model to a bilinear optimisation problem that simultaneously determines:i) a color correction matrix to transform the RGB spectral response to XYZ color space; and,ii) parameters of the color filter.The method further executes computer program instructions configured to solve the bilinear optimisation problem and, then provides a color filter using the parameters.