COMPARISON OF REFERENCE-WHITE STANDARDS FOR VIDEO DISPLAY UNITS

There are two common chromaticity standards for video-display-unit reference white, one standard at 6500 K correlated color temperature (CCT), called D65 for short, and the other, an industrial standard, at 9300 K CCT. The choice of D65 evolved from the NTSC specification for television receivers based on Illuminant C-an average daylight at 6800 K CCT. Although originally the studio illumination was much redder than D65, modern television cameras operate in daylight, so a daylight white standard is most likely to allow exact color reproduction at the receiver. Hence average daylight is the most natural white point. However, many manufacturers chose 9300 K because the chromatic efficiency of the prevailing blue phosphors was greater than that of red or green phosphors, because viewers did not object to a blue color bias, and because 9300 K was bluer than any of the prevailing ambient illuminations. In the years since the adoption of the 9300-K standard, these facts underwent some change, and also VDUs came to be used for graphics as well as for television. This paper outlines the reference-white problem, and suggests a reevaluation of the 9300-K standard.