Specification and control of screen colour in high-resolution monitors

The paper reports the development and use of accurately calibrated on screen colour. High resolution colour CRT monitors provide an excellent basis for this, but it is not easy to insure that the stimulus is of exactly the correct specification. To achieve a wide range of precise stimuli, a method is needed for measuring CIE coordinates of on-screen colour and the Minolta TV Analyzer provides a rapid an effective method. In general the Minolta achieves deviations from absolute of within +/- 0.005 or better in 1931 CIE two-degree xy coordinates over a full range of colours as calibrated against a fullspectrophotometer, such as the Bentham tele spectro radiometer (TSR). The second important component in delivering accurate on-screen colour is a numerical method for converting xyz coordinates to monitor drive (RGB) red, green and blue values. The process involves two stages. In the first, xyz coordinates are transformed into RGB coordinates using a matrix transposition. The second stage involves compensation for the non-linear relationship between drive voltage and screen luminance. Our research has shown that these excitation curves can be measured very precisely.