1. A color information processing method comprising: inputting reference data including color information about each pixel or each pixel group of a reference medium and evaluation target data including color information about each pixel or each pixel group of an evaluation medium by an input means; performing an image matching process of image matching the input reference data and evaluation target data by an image processing means such that pixel levels thereof correspond to each other, the image matching process including positioning images of the reference medium and the evaluation medium on a common coordinate axis of the images and removing a relative size difference and relative distortion between the images of the reference medium and the evaluation medium; setting a specific area which is a unit of evaluation and includes a plurality of pixels to each data item subjected to the image matching process by an area setting means; and comparing the color information items about each pixel or each pixel group in the reference data and the evaluation target data in the set specific area to calculate a color difference and performing an averaging process to calculate an average evaluation result for the specific area by a calculation means.