1. An image processing apparatus comprising: an image display unit which displays a material image in a first area of a display device and displays an original image in a second area of the display device; a detection unit which receives input to designate a first point in the first area of the display device, a second point in the second area of the display device, and one or more third points in the second area of the display device; a relationship determining unit which sets the first point as a first reference position and the second point as a second reference position, and which determines a correspondence relationship between the first reference position and the second reference position, such that the first reference position and the second reference position correspond to each other; an allocation region determining unit which determines an allocation region in the second area that is allocated to a partial image cut from the material image based on the one or more third points; and a cut region determining unit which determines a cut region in the first area where the partial image is cut from the material image based on the correspondence relationship and the allocation region that is allocated to the partial image; wherein the image display unit displays the partial image cut from the material image in the allocation region in the second area of the display device in combination with the original image so as to display a combined image.