1. An image processing apparatus which generates an image to simulate on the basis of a composite image of a real image and a virtual image, comprising: storage means for storing a first parameter and a second parameter to generate an image corresponding to a designated characteristic; acquisition means for acquiring a real image; conversion means for converting the real image acquired by the acquisition means on the basis of the first parameter; generation means for generating a virtual image on the basis of the second parameter; composition means for compositing the real image converted by the conversion means and the virtual image generated by the generation means; and display means for displaying an image composited by the composition means.