False Color Suppression in Demosaiced Color Images

In a single-chip digital color camera, a color filter array (CFA) is used to obtain sampled spectral components (red, green and blue) in an interleaved fashion. A color demosaicing operation is then carried out to determine the missing spectral components at every location. One of the problems in color demosaicing is that many of the interpolated images are affected by colored artifacts near the edges creating false colors. The problem is more severe if the edges are achromatic. In this paper we propose the use of median filtering for suppressing this phenomenon. We have considered a set of existing interpolation algorithms and presented their performances in interpolating mosaiced patterns. Next we have carried out median filtering of the chrominance components of the demosaiced images. In each case, the post-processing has remarkably improved the quality of the reconstructions. The observations are verified by both quantitative measures for expressing the quality of reconstruction as well as by visual examinations of the reconstructed images.