1. An image processing apparatus for processing image data of an object shot by an imaging unit and encoded, comprising: illumination controlling means for controlling emission of light to the object with a setting amount of light from the illumination unit when shooting the object by the imaging unit; region extracting means for independently extracting the image data of an object region indicating the object, and image data of a background region indicating a background other than the object from reference image data out of two pieces of image data based on more than one piece of image data, respectively shot by the imaging unit and encoded at each change in an amount of the light from the illumination unit under control by the illumination controlling means; filter processing means for applying a filtering process with the blurring effect to at least one piece of the image data of the object region and the image data of the background region, both extracted by the region extracting means; and combining means for generating combined image data of the reference image data with the image data subject to the filtering processing by the filter processing means out of the image data of the object region and the image data of the background region.