1. An image processing device comprising: a shading correcting unit that carries out shading correction for subject images picked up by imaging elements; a distortion correcting unit that corrects distortion of the subject images; a lens-characteristic estimating unit that estimates lens characteristics of imaging lenses that capture light made incident on the imaging elements; a resolution restoring unit that carries out, based on the estimated lens characteristics, resolution restoration processing for the subject images; a block matching unit that carries out block matching processing for alignment of the subject images; and a demosaicing unit that generates a color image by performing demosaicing processing for image data obtained by the block matching processing, wherein the shading correcting unit, the distortion correcting unit, the lens-characteristic estimating unit, and the resolution restoring unit carry out, on a plurality of sub-camera modules including the imaging elements and the imaging lenses, signal processing for each of image data obtained by the sub-camera modules.