1. An image processing apparatus comprising: a first display unit which displays a material image in a first area on a display device and displays an original image in a second area on the display device; a detection unit which detects a position on the display device designated from an outside; a relationship determining unit which sets a designated position in the first area detected by the detection unit as a first reference position, and sets a designated position in the second area detected by the detection unit as a second reference position, and which determines a correspondence relationship between each position in the first area and each position in the second area 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 based on a detection result of the detection unit; a cut region determining unit which determines a cut region in the first area to correspond to the allocation region determined by the allocation region determining unit based on the correspondence relationship determined by the relationship determining unit; and a second display unit which displays a partial image cut from the material image based on the cut region determined by the cut region determining unit in the allocation region determined by the allocation region determining unit to display a combined image.