1. An image processing device for processing input image data made up of a predetermined number of pieces of pixel data obtained by an image-taking device having a predetermined number of pixels having time-integration effects, said image processing device comprising: region specifying means for specifying, based on said input image data, one or the other of a mixed region made up of a mixture of a foreground object component configuring foreground objects and a background object component configuring background objects, and a non-mixed region made up of one of a foreground region made up of said foreground object component and a background region made up of a background object component configuring said background objects, and outputting region specifying information corresponding to the results of specifying; separating means for separating said input image data in at least said mixed region into said foreground object component and said background object component, corresponding to said region specifying information; and processing means for individually processing said foreground object component and said background object component, corresponding to the results of separation.