1. An image processing apparatus comprising: a plurality of extraction units that extract a plurality of spatial feature amount signals of an input image signal formed by a two-dimensional image signal; a plurality of enhancement processing units that generate a plurality of enhancement signals by performing an enhancement process for each of the plurality of feature amount signals; and a plurality of first image generation units that generate a first viewpoint image for each of the plurality of enhancement signals by adding the plurality of enhancement signals to the input image signal, wherein the plurality of extraction units extract a plurality of spatial feature amounts of the input image signal formed by a two-dimensional image signal such that a signal difference between viewpoints of viewpoint images which are obtained in order of magnitude of addition values of the enhancement signals added to the input image signal is a predetermined value, and both of two viewpoint images where the signal difference between viewpoints is equal to twice the predetermined value form a left eye image and a right eye image for realizing three-dimensional stereoscopic vision, and wherein at least one of the plurality of extraction units, the plurality of enhancement processing units, and the plurality of first image generation units are implemented via a processor.