A joint demosaicking-zooming scheme for single chip digital color cameras

Demosaicking and zooming are important for the quality of digital images in resource-constrained single chip devices such as wireless camera phones and vision-based pocket devices. The color artifacts introduced in the demosaicking process can be magnified in the subsequent zooming process and vice versa. This paper presents a joint demosaicking–zooming scheme by exploiting the fact that red/green and blue/green color difference signals are much smoother than the original red, green and blue signals. The color difference signals are computed using the high spectral–spatial correlations in the color filter array (CFA) image. The computed color difference signals are used to recover the green channel, which is then enlarged using an edge guided zooming scheme. The enlarged red and blue channels are obtained by adding the correspondingly enlarged red/green and blue/green color difference images to the enlarged green channel. Experimental results show that the proposed joint demosaicking–zooming scheme performs well in both visual perception and PSNR measurement, suppressing many color artifacts arising from demosaicking as well as zippers and rings arising from zooming.