1. An image processing apparatus comprising: a computer storage for storing an image; a target area specifying means for specifying a target area determined based on a body portion of a person constituting an object in the image; and an image generating means for generating an image subjected to a gradation process as an image processing on a target area specified by the target area specifying means, wherein the target area specifying means includes: a detection means for detecting the body portion of a person constituting an object in an image; and a specifying means for specifying the target area based on the body portion detected by the detection means, wherein the image generating means generates an image subjected to the image processing in an area within a target area specified by the target area specifying means, which area has a color component equal or near to the main color component representing the body portion constituting a reference of the target area, and wherein the image generating means includes: a strength value calculation means for calculating a strength value indicating the degree to which the color component of each pixel of the image to be processed is near to the main color component representing the body portion constituting a reference of the target area.