Accuracy of colour production on a CRT display as a function of the measurement instrument used for calibration

Abstract

Abstract— This investigation determined the error associated with colour reproduction when different light meters were used to characterize a CRT. Luminance measurements were taken with three light‐measuring instruments to produce gamma tables. The tables were used to calibrate 28 colours. Results showed that the most acceptable instrument was one that accurately measured light below 0.001 cd/m2 and that used colour‐matching tables to weight the radiant energy. Less‐sensitive instruments that used fixed filters to model the colour‐matching functions produced colours that were perceptibly different from the specified colours. The reproduction errors were evaluated against colour discrimination thresholds and ΔE*. If accurate reproduction of luminance is not essential, a less‐sensitive instrument with a cutoff of 0.01 cd/m2 and three separate filters for modeling the colour‐matching functions may be adequate. Complete gamma‐correction tables (voltage input/luminance output) for each gun were not necessary. Accurate colour calibration can be based on a limited number of luminance measurements plus an interpolation procedure to determine the intervening values in the gamma tables. The reliability of the initial characterization was tested after an interval of 9 months. The maximum luminance of the monitor decreased considerably over this time period. A simple recalibration method, outlined by Lucassen and Walraven (Ref. 1) was effective in restoring luminance accuracy. This method allows for periodic adjustments to the luminance output on a CRT using a small number of measurements.