Multispectral Sensor Color Conversion via Matrix Optimization
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Solution Overview
Problem
Existing methods for converting multispectral image sensor (MIS) measurement data into a color space are inefficient due to the need for large amounts of training data, high computational requirements, and significant memory usage, especially when dealing with various light sources and non-unique spectral estimation solutions.
Innovation Solution
A computer-implemented method that converts MIS measurement data into a color space based on an arbitrary correlated color temperature (CCT) by obtaining reference transformation matrices, optimizing, and normalizing them to generate a target transformation matrix for accurate color conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multilayer perceptron (MLP) is used for color conversion, then color conversion capability is achieved, but large amounts of training data, computational resources, and memory space are required
Solution Approach 1:
The patent replaces the complex MLP neural network system with a simplified linear transformation system using a 3x3 matrix. Instead of using a deep learning model with multiple layers and activations, the invention uses a direct mathematical transformation: T_ref = M_ref × S_ref, where T_ref is the reference color space, M_ref is the 3x3 transformation matrix, and S_ref is the sensor signal. This substitution dramatically reduces computational complexity while maintaining color conversion capability.
Solution Approach 2:
The patent changes the approach from learning complex non-linear parameters in an MLP to determining simple linear parameters in a 3x3 matrix. The transformation matrix parameters are derived directly from the sensor's spectral sensitivity characteristics and the target color space definition, rather than being learned from large training datasets. This parameter simplification reduces both computational burden and memory requirements.
2Ease of operation
If spectrum estimation is performed from image sensor signal, then color space values can be acquired, but estimation accuracy is relatively low due to non-unique solutions
Solution Approach 1:
The patent extracts only the necessary color space information directly from the sensor signal through linear transformation, rather than attempting to reconstruct the full spectrum. By using the transformation T_ref = M_ref × S_ref, the method extracts colorimetric parameters (XYZ values) without needing to solve the ill-posed spectrum estimation problem. This extraction approach avoids the non-unique solutions inherent in high-dimensional spectrum reconstruction from low-dimensional sensor data.
3Measurement precision
If reference transformation matrices are optimized without regularization, then fit to training data improves, but overfitting occurs and generalization deteriorates
Solution Approach 1:
The patent incorporates a feedback mechanism through the loss function that includes both a data fidelity term and a regularization term: L = ||T_ref - M_ref × S_ref||² + λ||M_ref||². The regularization term provides feedback that penalizes overly complex transformation matrices, preventing overfitting. This feedback loop ensures that the optimized matrix maintains good generalization capability while still fitting the training data adequately.
Solution Approach 2:
The patent applies partial optimization by not seeking the perfect fit to training data, but rather a sufficient fit that generalizes well. The regularization parameter λ controls the balance between fitting accuracy and model simplicity. By accepting a slightly suboptimal fit to training data in exchange for improved generalization, the method avoids overfitting while maintaining practical accuracy for color conversion applications.
Data Source
AI summary
Provided are an electronic device and a method of converting measurement data obtained by a multispectral image sensor (MIS) into a color space based on an arbitrary correlated color temperature (CCT). The method comprises obtaining reference transformation matrices configured to convert the measurement data obtained by of the MIS into a first color space based on each of reference CCTs, and, based on the reference transformation matrices, obtaining a target transformation matrix configured to convert the measurement data obtained by the MIS into the first color space based on a target CCT different from the reference CCTs.


