dividing the blurred image into a plurality of overlapping regions each having a size and an offset from neighboring overlapping regions along a first direction, wherein the size and offset are determined by a period of a ringing artifact in the blurred image if the blurred image has been filtered, or by obtained blur characteristics relating to the blurred image and/or attributable to the optical system, or by a detected cause capable of producing the blur characteristics;

stacking the plurality of overlapping regions to produce a stacked output, wherein the overlapping regions are sequentially organized along the first direction;

convolving the stacked output through a first convolutional neural network (CNN) to produce a first CNN output having reduced blur as compared to the stacked output; and

assembling the first CNN output into a re-assembled image.