Enhancing Angular-Dependent Color Performance of TFT-LCDs by Transmittance Scaling

Publisher： Society for Imaging Science and Technology

ISSN： 2166-9635

Source： Color and Imaging Conference, Vol.2006, Iss.1, 2006-01, pp. : 153-158

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Abstract

This paper presents an algorithm for minimizing color shift of a liquid crystal display (LCD). In a normally white, twisted nematic-type LCD, the angular-dependent color shift is inversely proportional to its panel transmittance. By increasing the panel transmittance and decreasing the backlight intensity simultaneously, we can reduce the angular-dependent color shift and power consumption at the same time. In this study, first, we characterized the angular-dependent luminance reduction and color shift of a 19″ TFT-LCD. Second, we conducted experiments to characterize the human factors of viewing angle variation. Since dynamic range also decreases as the viewing direction increases, tone re-mapping is required. We conducted psychophysical experiments to study the interaction between perceived contrast and brightness of pictorial images. Based on the experimental results, we proposed an algorithm that scales the transmittance of red, green, and blue channels independently subject to image distortion constraints. We implemented the proposed algorithm by prototyping an RGB LED-backlit LCD monitor and driving modules to demonstrate the concept.