Color measurements using digital photography

This article describes concept of using digital camera for color measurements. Imaging colorimeter system uses data from RAW file, acquisited by digital camera. They include unprocessed data, read directly from imaging element. The first stage of analysis is an image correction to give linear dependency of pixel value and luminance. Those corrections eliminate influence of exposure and camera optics on measuring results. Since digital camera channels spectral sensitivities (RGB) are different from spectral sensitivities of normal color observer (XYZ CIE), transformation between this color systems was made. It allows to obtain color measurement results scaled as tristimulus values XYZ At present phase of project a linear transformation was used. Its parameters were calculated by means of linear regression method. Input data was taken by measurement of special prepared learning samples. Test measurements with prepared imaging colorimeter were made and an average error was calculated.