Image processing apparatus configured to detect object included in image and method therefor

An image processing apparatus comprising:

• an image acquisition unit configured to acquire a plurality of input images which are serially photographed;
• a detection unit configured to detect a plurality of objects from each input image acquired by the image acquisition unit;
• an association unit configured to associate a plurality of objects detected from a past input image with a plurality of objects detected from a current input image;
• a calculation unit configured to, calculate a moving amount for each of the plurality of objects mutually associated between the past input image and the current input image;
• an identification unit configured to identify an undetected object that has been detected from the past input image but has not been detected from the current input image based on a result of association by the association unit;
• a determination unit configured to determine a relationship between moving amounts and sizes of the detected objects based on the calculated moving amount for each of the detected objects and a size thereof;
• a first estimation unit configured to estimate a moving amount of the undetected object based on a size of the undetected object and the determined relationship between moving amounts and sizes of the objects;
• and
• a second estimation unit configured to estimate a position and a size of an object in the current input image that would be associated with the undetected object in the past input image based on the estimated moving amount of the undetected object.