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; calculating an evaluation result by a calculation means, for each range corresponding to each ink key which controls an ink amount in the reference medium and the evaluation medium, by comparing the color information of both the reference data and the evaluation target data about each pixel or each pixel group based on the reference data and the evaluation target data in a specific area which is a unit of evaluation; and adjusting a printing color of a printing machine based on the evaluation result by an image processing means.