Effects of ambient illumination and screen luminance combination on character identification performance of desktop TFT-LCD monitors

This study investigated the effects of ambient illumination and screen luminance combination on character identification performance of thin film transistor liquid-crystal displays (TFT-LCD) monitors. Results showed that character identification performance was not significantly affected by ambient illumination at normal office levels. Further, the effects of ambient illumination regarding CRT use as found in previous studies may apply to TFT-LCD at normal office ambient illumination levels. Though our results showed that screen luminance combination did significantly affect character identification performance, the effect of screen luminance combination may be disregarded as the luminance combination of screen is adequate and the contrast ratio is high enough. In general, character identification performance increased with increasing background screen luminance. However, under high contrast ratio, C16L showed character identification performance lower than C8H. These results seem to indicate that character identification under relatively high ambient illumination is more affected by background luminance of the screen than contrast ratio or contrast sensitivity. Therefore, considering screen luminance combination and contrast ratio simultaneously may be more appropriate than considering contrast ratio alone. The TFT-LCD is fast becoming the most optimal choice in VDT display today. Ambient illumination and screen luminance combination are the key factors affecting character identification performance for TFT-LCD users. The results from this study may improve the visual performance for TFT-LCD users.