Abstract: This paper proposes a new colorimetric analysis algorithm based on smartphone images. Conforming to human eye vision, it has the advantages of minor calculation and best calculating stability. This method converts the color information of the original nonlinear RGB color space to the CIELab color space that conforms to the human vision, therefore the reference color closest to the test color can be accurately picked. Meantime, "vertical point method" is proposed innovatively to further quantify the similarity of color information and realize the quantitative analysis of urine test strips. As for the experiment, the pH (4.59.5), glucose content (060 mmol/L) and protein content (04 g/L) in artificial urine were quantitatively analyzed by taking photos of urine test strips in an ambient light-isolated box, and visual colorimetry was used as a control. The results show that the proposed colorimetric algorithm is not only accurate, reliable, reproducible and computable, but also suitable for application in urine test strip colorimetric analysis based on mobile phone images.

Key words: CIELab color space, colorimetric analysis, urine test strips, smart phone