A Study on Improving the Image Quality of TFT/LCDs by both Photometric Measurements and Subjective Evaluations

To improve the image quality of thin film transistor liquid crystal displays (TFT/LCDs), we performed photometric measurements and subjective evaluations on nine kinds of TFT/LCDs with different physical characteristics. The photometric measurements evaluated reflection characteristics, luminance contrast, gamma curve, primary color points, white points, luminance/color uniformity and effects of viewing angle. The subjective evaluations consisted of two sessions.In the first session, basic patterns such as all-pixels-on were presented and basic feelings such as sharpness of reflected images and color saturation were collected by the Scheffe's paired comparison method. At the other session, seven kinds of general patterns such as an MS-windows desktop and natural images were displayed, and distinctive features of the image quality of each display were summarized.It was found that the feelings when the basic patterns were displayed corresponded with the results of photometric measurements. Although it was difficult to estimate image qualities of general patterns from the measured photometric characteristics, white point was found to be one of the most important factors affecting image quality of TFT/LCDs among the above-mentioned characteristics.