To control rough surface touch of a transmission image in comparison with the conventional art.

An image formation device 1 includes: a rear concealment concentration interpolation part 60A that interpolates each concentration of concealment pixels concealed in a transmission image among pixels constituting a rear image by the concentration of unconcealed pixels; a transmission factor calculation part 608 that detects the transmission factor of the transmission image; a transmission image concentration interpolation part 609 that interpolates the concentration of a concentration-less pixel whose concentration in the transmission image is less than a predetermined value by the concentration of a concentration pixel whose concentration is at least the predetermined value; and a superposition region gradation calculation part 60C that compensates the concentration of each pixel at a part where the transmission image and rear image are superposed on the basis of the concentration after the interpolation of each pixel of the transmission image, the concentration after interpolation of each pixel of the rear image, and the transmission factor of the transmission image.