1. An image conversion apparatus comprising: a first calculation unit for executing, based on a first value used to obtain first coordinate values in a second image before first image conversion, which correspond to coordinate values of one pixel in a first image after the first image conversion, calculation of obtaining a second value used to obtain second coordinate values in the second image before the first image conversion, which correspond to coordinate values of a pixel adjacent to the one pixel in the first image after the first image conversion; a second calculation unit for executing calculation of obtaining the second coordinate values using the second value obtained by the calculation of the first calculation unit; a coordinate conversion unit for executing coordinate conversion of converting the second coordinate values obtained by the second calculation unit into third coordinate values for second image conversion of converting a third image into the second image; and an image conversion unit for executing the first and second image conversion of converting the third image into the first image, based on the third coordinate values converted by the coordinate conversion unit, wherein the first calculation unit iteratively executes one of addition and subtraction using a predetermined constant and an output of the first calculation unit as inputs so as to sequentially output a value corresponding to a multiplication result obtained by multiplying coordinate values of each of a plurality of adjacent pixels in the first image after the first image conversion by the predetermined constant.