Image quality evaluation of LCDs based on novel RGBW sub-pixel structure

Many display manufacturers have studied RGBW pixel structure adding a white sub-pixel to RGB LCD and recently revealed UHD TVs based on novel RGBW LCD. The RGBW LCD has 50% higher white luminance and 25% lower primary color luminance compared to RGB LCD. In this paper, the image quality of RGBW and RGB LCD was dealt with. Before evaluating them, TV broadcast video and IEC-62087 video were analyzed for test video clips. In order to analyze them, a TV reference video from TV broadcast content in Korea was firstly collected. As a result of TV reference video analysis, RGBW LCD was expected to improve image quality more because most of colors are distributed around white point and population ratio of achromatic colors is higher. RGB, RGBW and RGBW using wide color gamut (WCG) backlight unit (BLU) LCDs were prepared, and a series of visual assessments were conducted. As a result, RGBW LCD obtained higher scores than RGB LCD about four attributes (‘Brightness’, ‘Naturalness’, ‘Contrast’ and overall image quality) and ‘Colorfulness’ was not higher score than RGB LCD in test still images. RGBW LCD’s overall image quality in the TV reference video clips also was assessed higher than RGB LCD. Additionally, RGBW LCD using WCG BLU shows better performance about especially ‘Colorfulness’ than RGBW LCD.