1. An image processing device comprising: a central processing unit (CPU); and a memory, connected to the CPU, having instructions stored therein that when executed by the CPU comprise: a patch generation unit which generates an input patch used for comparison on the basis of an input image; a modification parameter estimation unit which estimates a parameter used in blurred modification on the basis of the input image; a blurred image generation unit which generates a blurred image on the basis of a learning image by using the parameter; a patch pair generation unit which generates a patch pair used to compose a restoration image on the basis of the blurred image and the learning image; a selection unit which selects a patch pair used to compose the restoration image on the basis of the input patch; a composition unit which composes the restoration image on the basis of the patch pair selected by the selection unit, and an evaluation unit which evaluates the patch pair selected by the selection unit, wherein the modification parameter estimation unit estimates the parameter on the basis of a result of the evaluation.