Colorimetric calibration of a video digitizing system: Algorithm and applications

Abstract

Abstract In principle, digitized color video images should be rich and convenient sources of colorimetric information. In practice, these advantages are offset by the difficulty of reliably translating the video camera's output into colorimetric variables. A solution to this problem is outlined here, one which exploits the fact that spectral reflectances of many natural materials vary slowly in the visible. A characteristic vector analysis of reflectances for a set of such materials leads to an algorithm that gives colorimetrically accurate spectral reflectances from the red‐green‐blue output of a video digitizing system. Prior knowledge about the illumination leads to chromaticity and luminance information, which can be comparable in quality to that obtained from a spectrora‐diometer. Some sample retrievals are shown for the algorithm. Since it is designed to correct color biases that are unknown initially, the algorithm has the advantage that images from many sources can be analyzed.