1. A color processing apparatus comprising: a reader, arranged to read an image of an original document to which position information and pixel values of a plurality of pixels in an image used to print the original document are added using a digital watermark technique; an extractor, arranged to extract the position information and the pixel values from the image read by the reader; an acquisition section, arranged to acquire pixel values of a plurality of positions indicated by the position information in the image read by the reader; and a corrector, arranged to correct color of the image read by the reader, using the pixel values extracted by the extractor and the pixel values acquired by the acquisition section.