Color Correction Technique using an Artificial Color Board and Root-polynomial Color Correction for Smartphone-Based Urinalysis

Urinalysis is a method that uses urine test strips containing indicators in the form of reagents that will change color when reacting with certain substances in urine that have been determined. Many researchers have developed readings of color change test strips using smartphones due to being portable and easier to use. However, the color information of the obtained image is unstable due to several factors, such as environment light, sensor characteristics, and other stability factors. Color correction was performed to consistently produce color information using the Root-polynomial color correction (RPCC) algorithm based on the color reference standard in Artificial Color Board. The color correction technique was evaluated using images taken with a color temperature variation of 2500°K – 8500 °K that were recorded using Huawei Nova 5T and Samsung Galaxy A51. The results show that the RPCC method has a good and stable performance on every cellphone used with a color correction evaluation value ($\Delta$E) of 1.8 – 2.6. The results show that the artificial color board and RPCC method can also minimize color temperature so that the color measurement results remain accurate.