In the past, colorimetry was separated into two categories: visual colorimetry and photoelectric colorimetry. Visual colorimetry measures concentration by observing the color change of the target solution with the naked eye. However, in visual colorimetry, it is challenging to identify minute color variations with the unaided eye, although photoelectric colorimetry has higher measurement precision than visual colorimetry. In modern society, it is becoming increasingly important to gather and share analytical data quickly on the spot. As a result, digital image colorimetry (DIC) has become a popular area of research. DIC is recognized as a robust, quick, and affordable analytical approach to assess the target analyte with respect to the color change produced by its chemical reaction. The color thus produced is captured by a digital camera and then analyzed by color analysis apps/software. With the impressive increase in the use of this technique, several modalities of color detection were developed and improved to fulfill the demands of conducting qualitative, semi-quantitative, and completely quantitative analyses of many analytes. The chapter summarizes the principle and procedure of DIC and also presents the applications of DIC in drug analysis.
