Color image quality evaluation of tablet display under different ambient illuminance levels

• Main Authors: Tai-Yu Chiang, 江泰佑
• Other Authors: Hung-Shing Chen
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/we8afj

碩士 === 國立臺灣科技大學 === 光電工程研究所 === 107 === In this study, the color gamut and tone reproduction curve of LCD (liquid crystal display) of tablet display under different ambient light levels are studied, and then the visual evaluation of human factors experiments is carried out. The research is divided into the following two experiments. Experiment 1 is standardized modeling of color gamut and tone reproduction curve and explores the use of a colorimeter to measure LCD. Under consideration of external ambient light and internal light leakage, reference white selection, and standardization under different ambient light levels. LCD can be compared at different ambient light levels at the same time, clearly showing changes in color gamut and tone curve. The results show that when the ambient light level changes from a dark room to a bright room, the color rendering capability of LCD is affected, with a tendency to have a smaller color gamut volume and a narrower lightness range. It can also be seen that when the ambient light condition is changed from a dark room to a bright room, the gamma value of the calibrated tone reproduction curve becomes smaller. Experiment 2 is human eye evaluation using a calibrated desktop LCD, with adjustable display corrected to the same color gamut as LCD, wherein LCD adjusted three settings and four ambient light levels, a total of twelve methods for human vision. The evaluation experiment explores the best similarity between the standard image of the adjustable display and the test image of the LCD. The result shows that when the different combination of software (X-rite ColorTrue) setting mode and ambient light, the dk_0 (darkroom setting, 0 lux), oe_500 (office room setting, 500 lux), bt_1000 (bright room setting, 1000 lux) similarity is better, furthermore, the result of Experiment 1 is continued. It can be inferred that the value of the tone reproduction curve and linear transformation matrix in the display conversion calculation process are changed due to the software setting mode compensation, which affects the similarity of the human eye evaluation. Based on the above two experimental results, a compensation model for predicting tablet displays under different ambient light is proposed to provide a suitable range of color quality to achieve color consistency between different mobile devices.