1. An image processing apparatus comprising: an image acquiring unit that acquires an image of a subject imaged by an image capturing lens; a face detecting unit that detects face information corresponding to a person's face from the image acquired by the image acquiring unit; an image angle-of-view calculating unit that calculates an angle of view of a portion including the face in the image based on the face information detected by the face detecting unit; and a correction necessity determining unit that determines whether distortion correction of the image is need to be performed, based on the angle of view calculated by the image angle-of-view calculating unit and distortion characteristics of the image capturing lens.