Using camera of a cell phone as a spectrophotometer in the outdoor usage

To use a mobile phone camera as a spectrophotometer, two steps are usually required. In the first step, the output RGB values of a camera are converted to device-independent color values. Afterward, spectral reflection values are reproduced from those device-independent values. In this paper, the matrix method was used to convert two color spaces to each other in the first step. In the next step, spectral reflection values were reproduced using the principal component analysis (PCA) method. It was shown that the best result is obtained using light source D50/ standard observer in 1964 and light source A/ standard observer in 1931 in a way that the color of the second light source and observer are obtained through a conversion matrix from the color values of the first light source and observer.