CONSIDERATIONS ON THE CALIBRATION OF COLOR DISPLAYS ASSUMING CONSTANTCHANNEL CHROMATICITY

To calibrate a CRT color monitor, several assumptions are often made a bout its performance, one of the most accepted being constant channel chromaticity. However, when the measurements are taken in a extended f ield of CRT screen, where it is assumed that only one primary phosphor is excited, the relative spectral radiance of the other primary phosp hors that are contained in that field also contributes, if the backgro und luminance is not zero. This contribution is greater at low levels of RGB channel stimulation and would invalidate the results obtained w ith calibration methods based on the hypothesis of constancy of chroma ticity coordinates of RGB channels. We have studied this effect on the calibration of the CRT color monitor and, as a result, we propose a c alibration that takes this effect into account. To evaluate the accura cy of the method, we have calculated color differences between the chr omaticity that we wanted to reproduce and the one displayed with the C IELUV color-difference formula, and the color tolerances with the line element of MacAdam ellipses. (C) 1995 John Wiley & Sons, Inc.