The present invention relates to an image processing apparatus in which a mixture ratio indicating the mixture state of a plurality of objects can be detected. A normal-equation adder 441 extracts mixed pixel data, and also extracts background pixel data corresponding to the mixed pixel data so as to generate relational expressions for the mixed pixel data and the background pixel data. A normal-equation calculator 442 detects a single mixture ratio in accordance with a predetermined number of consecutive frames based on the relational expressions. The present invention is applicable to an image processing apparatus in which a difference between a signal detected by a sensor and the real world is taken into consideration.