1. An image processing apparatus for processing image data which is formed of a predetermined number of pixel data, having a plurality of types of components at the same pixel position, 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 said image data, a mixed area in which foreground object components which form a foreground object and background object components which form a background object are mixed; and mixture-ratio detection means for detecting, in correspondence with said image data, the mixture ratio indicating the ratio of the mixture of said foreground object components to the mixture of said background object components in a mixed area in which said foreground object components and said background object components are mixed, wherein at least one of said area specifying means and said mixture-ratio detection means performs image processing on the basis of said plurality of types of components.