1. An image processing apparatus comprising: an image input unit configure to input an image of a source document; a direction detection unit configure to detect a direction of the image; an image region detection unit configure to detect a header of a specific region of the image; an effective image region designation unit configure to designate an effective image region for the image; and an image processing unit configure to, when the effective image region is output as an output image based on the header of the specific region detected by said image region detection unit, and when the direction of the image is not a predetermined direction, process the image to have the predetermined direction.