1. An image processing apparatus for processing image data which is formed of a predetermined number of pixel data obtained by an image-capturing device including a predetermined number of pixels, the pixels having a time integrating function, said image processing apparatus comprising: area specifying means for specifying, in correspondence with the image data, a mixed area in which foreground object components forming a foreground object and background object components forming a background object are mixed and a non-mixed area formed of a foreground area consisting of only the foreground object components and a background area consisting of only the background object components; and mixture-ratio estimating means for estimating, based on a ratio of a width of the mixed area in a predetermined direction with respect to a moving direction of the foreground object component, the width of the mixed area being specified by the area information, to a distance from a position of a designated pixel to an edge of the mixed area in the predetermined direction, a mixture ratio indicating the ratio between the foreground object components and the background object components of the designated pixel.