An image processing device capable of determining a mixing ratio indicating the state in which a plurality of objects such as a background image and an image of a moving object are mixed. An addition unit (502) extracts not only the background pixel data but also data on a pixel of interest and its adjacent pixels. The addition unit (502) generates a plurality of relations among the pixel of interest, the adjacent pixel data, and the background pix el data. An arithmetic unit (503) computes the mixing ratio indicating the mixe d state of the objects in the real world with respect to the noted pixel by using the relation. This an image processing device in which the difference between the signals produced by a sensor and the real world is taken into consideration is provided.
