1. An image determination apparatus, comprising: image data receiving means for receiving image data comprising pixels formed of RGB which are three primary colors of light; first comparing means for comparing a first color saturation value determined from color components of each pixel of the received image data to a first threshold value, reversed image calculation means for calculating color components of reversed images acquired by subtracting said color components from a possible maximum value of said color components of each of said pixels, second comparing means for comparing a second color saturation value determined from said color components of said reversed image to a second threshold value, and color region determination means for determining whether there is color or monochrome based on results of said first comparing means and said second comparing means.