CSD-A New Unified Threshold Metric of Evaluating LCD Viewing Angle by Color Saturation Degradation

Abstract

Lower luminance contrast ratio and chromatic changes affect the visual performance (i.e. color shift) of a thin-film transistor liquid-crystal device (TFT-LCD) at large viewing angles. The de facto method of defining viewing angle, contrast ratio of luminance, fails to represent the substantial visual performance viewed at a larger angle. We found the degradation of color saturation, dS*/d theta, to be an appropriate metric to aid the conventional viewing angle definition (CR >= 0). We empirically determined the threshold for defining the color viewing angles of TFT-LCDs, CVA = {theta parallel to dS*/d theta vertical bar <= 0.03} which reflects the variation not only in chromaticity but also in luminance. The proposed metric was evaluated by psychophysical experiments, whose results validate the efficacy of the proposed metric.