An image reading out apparatus reads out a partial image in a frame of an image within an image sensing unit, and outputs image data corresponding to the frame of the image and the partial image to an image development processing unit. A detection unit detects an object in a frame of a first image read out from the image sensing unit, and detects a moving speed of the object. A control unit (i) determines an area corresponding to the object, and (ii) controls, in accordance with the moving speed of the object detected by the detection unit, an interval of time to read out the partial image in the area in a frame of a second image within the image sensing unit. A reading unit reads out the frame of the first image and the partial image within the image sensing unit.