Abstract
The purpose of this study is to propose a criterion to evaluate brightness uniformity of LCDs (Liquid Crystal Drystal Displays)For this purpose. it is necessary to increase the understanding of human sensibility to brgltlness uniformity: At first we, performed a kind of psychophysical method using CG patterns displayed on a CRT monitor. The result shows that the brightness gradients determine the degree of brightness uniformity. In the second step, brightness gradients and sensory scores by human evaluation were measured in uneven regions on LCDs. The gradients were calculated by digital image processing techniques. The sensory scores were quantified from experimental results by a kind of paired comparison method. A strong correlation (r2=0.90) is shown between the gradient and the sensory score. In the next step. parameters of gradient image histogram and sensory scores are measured for whole surface of LCDs. Strong correlation (r2=0.86) is shown between average gradient for whole surface and sensory score by the majority of testee and maximum gradient. agree with other testee (r2=0.71). Measuring error using the parameter is almost the same as human evaluating dispersion. By those experiments. it is shown that the brightness uniformity can be evaluated agreeing with human sensibility by image processing technique.
