Lossless and reversible colour space transformation for Bayer colour filter array images

Abstract

We present two variants of a colour space transformation algorithm to encode Bayer colour filter array images that are based on integer coefficients; as a result, the algorithms are fully lossless and reversible in nature. These transformation algorithms are derived using an optimisation model that reduces the spectral redundancy of Bayer colour components, which results in lower prediction error variance and inter-colour correlation. These methods, known as optimum reversible colour space transform (ORCT-1 and ORCT-2), improve the lossless bitrate of low complexity prediction model without using high complexity interpolation and inter-colour prediction scheme. Extensive experimentation is performed using five sets of test images for different lossless compression algorithms: JPEG-LS, JPEG-2000 and JPEG-XR. Experimental results show that, in all cases, the proposed schemes perform competitively with other methods with lower computational complexity, which makes them suitable for low-cost imaging applications.