Super-resolution Sharpening-Demosaicking with Spatially Adaptive Total-Variation Image Regularization

Abstract

We previously presented a demosaicking method that simultaneously removes image blurs caused by an optical low-pass filter used in a digital color camera with the Bayer’s RGB color filter array. Our prototypal sharpening-demosaicking method restored only spatial frequency components lower than the Nyquist frequency corresponding to the mosaicking pattern, but it often produced ringing artifacts near color edges. To overcome this difficulty, this paper introduces the super-resolution into the prototypal method. First, we for mulate the recovery problem in the DFT domain, and then introduce the super-resolution by the total-variation (TV) image regularization into the sharpening-demosaicking approach. The TV-based super-resolution effectively demosaics sharp color images while preserving such image structures as intensity values are almost constant along edges, without producing ringing artifacts, but it tends to flatten signal variations excessively in texture image regions. To remedy the drawback, furthermore we introduce a spatially adaptive technique that controls the TV image regularization according to the saliency of color edges around a pixel.