<title>Evaluation of the performance of color camera for measuring small color differences</title>

Abstract

Machine vision systems based on a color camera are increasingly used for color measurements under industrial conditions. An important problem in the measurement of small color differences is related to metamerism. But because color cameras and human vision have slightly different response functions, they produce different sets of 'tristimulus values' for the same object viewed under the same illumination conditions, and it can happen that metameric pairs for a human are discriminated very well by a color camera and vice versa. The purpose of the present research was to evaluate the performance of color camera for measuring small color differences. The tests were performed for the whole collection of the NCS Color Block viewed under three different illuminants: standard illuminant A, standard illuminant D65, and illuminant F11, and for two options of color camera, 8-bit and 12-bit. The results show some limitations with lower bit camera for accurate colorimetric measurements and good performance with the 12-bit camera in discrimination of very similar colors.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.