Quantifying color changes in chemical test pads induced by different concentrations of analytes under different lighting conditions
Inventors
Burg, Bernard • Zizi, Martin • Rowe, Aaron Alexander • Smart, Anthony • De Brouwer, Walter
Assignees
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Publication Number
US-11802839-B2
Publication Date
2023-10-31
Expiration Date
Abstract
Color quantification of chemical test pads and titration of analytes can be performed under different lighting conditions. In one embodiment, the lighting condition is estimated under which a digital image is captured and utilized to select a set of reference colors from which the quantified color is compared to determine the titration. In another embodiment, a plurality of comparisons are made with different lighting conditions with the result having the highest confidence level being selected to determine the titration.
Core Innovation
A diagnostic instrument for quantifying analytes includes a plurality of reference samples of different colors and at least one test medium containing a reagent that changes color in response to a concentration of a particular analyte in a biological sample. A digital image of at least a portion of the diagnostic instrument exposed to the biological sample is obtained using a digital camera.
At least one reference sample is identified in the diagnostic instrument, and a dominant camera-captured color of the reference sample and a dominant camera-captured color of the test medium are determined. Lighting conditions under which the digital image is obtained are estimated, and the dominant camera-captured color of the test medium is corrected in response to a color correction factor derived at least in part from the dominant camera-captured color of the reference sample, to determine a corrected test medium color.
A test result is determined by comparing the corrected test medium color to a set of possible test medium colors corresponding to predetermined analyte concentrations. The set of possible test medium colors is responsive to the estimated lighting conditions under which the digital image is obtained, so the analyte concentration is determined from lighting-responsive color comparisons.
Additional refinements include removing color noise artifacts while determining dominant camera-captured colors using spatial guard bands and median filtering without altering raw colors, and applying color correction using a color reference bar to derive inverse mapping to a standard color space (MICC/ACC). Analyte determination is further refined using confidence tubes to reject out-of-range measurements and to shift color trajectories across lighting conditions, selecting the most confident result.
Claims Coverage
Two independent claims are present. Both claims share the core inventive structure of capturing a diagnostic instrument image with a portable camera, identifying color reference and test medium, estimating lighting, applying reference-derived color correction, and mapping corrected colors to lighting-responsive sets of possible colors to determine analyte concentration.
Lighting estimation with reference-derived color correction for dominant colors
Estimating lighting conditions under which the digital image is obtained and correcting the dominant camera-captured color of the at least one test medium in response to a color correction factor derived at least in part from the dominant camera-captured color of the at least one reference sample to determine a corrected test medium color.
Lighting-responsive mapping from corrected test medium color to predetermined analyte concentrations
Determining a test result including an analyte concentration by comparing the corrected test medium color to a set of possible test medium colors corresponding to predetermined analyte concentrations, wherein the set of possible test medium colors is responsive to the estimated lighting conditions under which the digital image is obtained.
Portable electronic device with camera-based identification of reference and test media
Identifying at least one of the reference samples and at least one of the test media in the digital image of the diagnostic instrument; determining a dominant camera-captured color of a reference sample and a dominant camera-captured color of the at least one test medium; estimating lighting conditions; correcting the dominant camera-captured color of the test medium using a color correction factor derived at least in part from the dominant camera-captured color of the reference sample; and determining an analyte concentration by comparison to lighting-responsive possible test medium colors corresponding to predetermined analyte concentrations.
The independent claims cover estimating lighting and computing a reference-derived color correction factor for dominant camera-captured colors and determining analyte concentration by comparing the corrected test medium color to a set of possible test medium colors that is responsive to the estimated lighting conditions.
Stated Advantages
Improves analyte concentration determination by making the set of possible test medium colors responsive to the estimated lighting conditions.
Reduces impact of color artifacts by removing color noise artifacts using spatial guard bands and median filtering while determining dominant camera-captured colors.
Rejects out-of-range measurements by using confidence tubes for decision-making.
Documented Applications
Quantifying color change of at least one test medium on a diagnostic instrument to determine analyte concentration of a biological sample.
Performing diagnostic tests of a biological sample using a system that includes a diagnostic instrument and a portable electronic device with a digital camera to capture and analyze color changes.
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