Biomarker Test Image Correction Using Calibration Array Shading
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Solution Overview
Problem
Existing image capture systems for biomarker tests face challenges in accurately correcting for illumination variations and shading, leading to inaccurate color mapping and biomarker concentration estimates due to device and environmental factors.
Innovation Solution
A computer-implemented method and system that uses a calibration array with colored patches to store reference color values, applies basis functions to model shading, and iteratively solves for a color correction matrix to interpolate accurate biomarker site colors, minimizing reliance on biomarker sites for shading correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional image capture systems are used for biomarker tests, then device simplicity is maintained, but color accuracy and measurement precision deteriorate due to illumination variations and shading
Solution Approach 1:
The patent applies preliminary action by pre-storing reference color values for multiple colored patches under controlled illumination conditions. These reference values are prepared in advance and stored in a data repository, allowing the system to later compare captured patch colors against these known references to calculate and apply correction factors for illumination variations and shading effects.
Solution Approach 2:
The patent introduces colored patches as intermediary elements that serve as reference standards within the image. These patches provide known color values that act as mediators between the illumination conditions and the biomarker measurement, enabling the system to characterize and correct for lighting variations without directly measuring the biomarker color under unknown illumination conditions.
2Measurement precision
If multiple colored patches are added to the calibration array for better shading correction, then color accuracy improves, but test complexity and required space increase
Solution Approach 1:
The patent applies universality by designing colored patches that serve multiple functions: they provide reference color values for illumination correction, establish shading gradients across the test surface, and enable calculation of correction factors. This multi-functionality allows the same patches to address multiple sources of error without requiring separate reference elements for each correction type.
Solution Approach 2:
The patent applies parameter changes by varying the colors and positions of patches in the calibration array to create known shading patterns. By strategically selecting patch colors and locations, the system can characterize illumination variations and shading effects across different regions of the test, enabling accurate correction without adding excessive complexity.
3Measurement precision
If biomarker sites are excluded from shading correction calculation, then color mapping accuracy improves, but the number of pixels available for solving correction parameters decreases
Solution Approach 1:
The patent applies segmentation by dividing the image into distinct regions: calibration array regions containing colored patches and biomarker test regions. The shading correction parameters are calculated using only pixels from the calibration array regions, excluding biomarker sites. This segmentation ensures that correction parameters are derived from known reference values rather than from the biomarker measurements themselves, preventing circular reasoning and improving accuracy.
Data Source
AI summary
Computer-implemented image correction for a biomarker test includes a biomarker test which has a calibration array and a biomarker site, wherein the calibration array comprises plural colored patches and the biomarker site is color-responsive to indicate a measurement of biomarkers present. The method comprises: storing a reference color value for each of the plural colored patches; receiving an image of the biomarker test; defining shading of pixels of the image as D, a combination of a plurality of basis functions; defining a color correction matrix, M having parameters that when solved correct color of the calibration array in the image to the corresponding stored values; solving D and M for pixels of the image excluding pixels of the biomarker site; using D and M to interpolate values for pixels of the biomarker site of the image to generate a color and shading corrected image of the biomarker site.