1. An image processing apparatus for processing an original image that is picked up, comprising: an image input part for inputting N original images having different exposure levels, where N is an integer of two or more, which are obtained by picking up images of the same subject in one of a simultaneous manner and a time-series manner; and a composite processing part for generating M output images, where M is an integer of one or more and less than N, by composing the N original images, wherein the composite processing part compares color component signals in each corresponding pixel position with each other between the N original images, and sets the color component signal that produces a higher chroma as a color component signal in each pixel position of the output image.