1. Introduction
RGBW is a new type of CFA (color filter array) pattern (Fig. 1) designed for image quality enhancement under low light conditions. Thanks to the higher optical transmittance of white pixels over conventional red, green, and blue pixels, the signal-to-noise ratio (SNR) of images captured by this type of sensor increases significantly, thus boosting the image quality, especially under low light conditions. Recently, several phone OEMs [1], [2], [3] have adopted RGBW sensors in their flagship smartphones to improve the camera image quality.