Joint chromatic aberration correction and demosaicking

Chromatic Aberration of lenses is becoming increasingly visible with the rise of sensor resolution, and methods to algorithmically correct it are becoming increasingly common in commercial systems. A popular class of algorithms undo the geometric distortions after demosaicking. Since most demosaickers require high frequency correlation of primary colors to work effectively, the result is artifact-ridden as Chromatic Aberration destroys this correlation. The other existing approach of undistorting primary color images before demosaicking requires resampling of sub-sampled primary color images and is prone to aliasing. Furthermore, this algorithm cannot be applied to panchromatic CFAs. We propose a joint demosaicking and Chromatic Aberration correction algorithm that is applicable to both panchromatic and primary color CFAs and suffers from none of the above problems. Our algorithm treats the mosaicing process as a linear transform that is invertible if luminance and chrominance are appropriately bandlimited. We develop and incorporate Chromatic Aberration corrections to this model of the mosaicing process without altering its linearity or invertibility. This correction works for both space variant linear filter demosaicking and the more aggressive compressive sensing reconstruction.