Universal Demosaicking for Interpolation-Friendly RGBW Color Filter Arrays

Interpolation-friendly RGBW color filter arrays (CFAs) and the popular sequential demosaicking contain the idea of computational photography, where the CFA and the demosaicking method are co-designed. Due to the advantages, interpolation-friendly RGBW CFAs have been extensively used in commercial color cameras. However, most associated demosaicking methods rely on strict assumptions or are limited to a few specific CFAs with a given camera. In this paper, we propose a universal demosaicking method for interpolation-friendly RGBW CFAs, which enables the comparison of different CFAs. Our new method belongs to sequential demosaicking, i.e., W channel is interpolated first and then RGB channels are reconstructed with guidance from the interpolated W channel. Specifically, it first interpolates the W channel using only available W pixels followed by an aliasing reduction technique to remove aliasing artifacts. Then it employs an image decomposition model to built relations between W channel and each of RGB channels with known RGB values, which can be easily generalized to the full-size demosaicked image. We apply the linearized alternating direction method (LADM) to solve it with convergence guarantee. Our demosaicking method can be applied to all interpolation-friendly RGBW CFAs with varying color cameras and lighting conditions. Extensive experiments confirm the universal property and advantage of our proposed method with both simulated and real raw images.