1. An image processing device comprising: an integrating unit configured to acquire, from a camera installed on a movable body, images that are captured by the camera while the movable body is moving and integrates the acquired images so as to generate an integrated image; a vanishing-point identifying unit configured to extract brightness edges from the integrated image and identifies an intersection point of lines determined by using the brightness edges as a vanishing point; a determining unit configured to determine whether a parameter of the camera has an appropriate value by using coordinates of the vanishing point identified and reference coordinates, the reference coordinates being coordinates of a reference vanishing point stored; and a correcting unit configured to correct the parameter of the camera in accordance with a difference between the coordinates of the vanishing point identified and the reference coordinates.