An ordinal direction driven gradient-based RGBW CFA demosaicking technique using a bayerisation process and polyomino theory

Recent studies have shown that panchromatic colour filter arrays possess better light intensity properties than the more prevalent Bayer array. This is an attractive property in integrated camera design. Demosaicking algorithms, however, focus primarily on Bayer-based cameras because of their simple demosaicking process. This paper presents a novel algorithm for use in the RGBW class of panchromatic arrays. It encodes light intensity information in a bayerisation conversion process and uses polyomino theory to define robust reconstruction interpolation weights. Performance of the proposed algorithm is assessed with established methods using two objective and commonly documented assessment measures (SSIM and CPSNR) over three (Kodak, USC-SIPI and Custom) image sets. An appreciable improvement is noted from MATLAB simulation, averaging 3dB above established techniques.