Two sub-pixel rendering algorithms of RGBW arrangement structure are proposed. The algorithms can keep the same resolution as traditional RGB arrangement, and improve the image brightness. The image processing includes two algorithms: mapping algorithm from RGB to RGBW and sub-pixel rendering algorithm of RGBW. The image receives new RGBW data from mapping algorithm of RGB to RGBW, and the algorithm improves the image brightness and keeps the color saturation. Sub-pixel rendering algorithm of RGBW makes the image realistic and soft, and it can reduce jagged sense. Simulation results show that the proposed RGBW arrangement and rendering algorithm can significantly improve the image brightness.