1. An image processing apparatus comprising: a processor that includes: a generating section configured to generate watermark data which denote a chromatic watermark and an achromatic watermark for copy control, which appear as a result of making a copy; and a composition section configured to generate composite image data which denote an image composed by joining an original image with a watermark, on a basis of the watermark data generated by the generating section and original image data obtained by reading an original document, wherein the generating section includes: a chromatic pattern generating section configured to generate a chromatic image pattern to form a chromatic watermark; and an achromatic pattern generating section configured to generate an achromatic image pattern to form an achromatic watermark, wherein the generating section generates watermark data on a basis of the chromatic image pattern generated by the chromatic pattern generating section or the achromatic image pattern generated by the achromatic pattern generating section, wherein the chromatic image pattern includes a first chromatic image pattern, which appears as a result of making a copy, wherein the achromatic image pattern includes a first achromatic image pattern, which appears as a result of making a copy, wherein a spatial frequency of the first chromatic image pattern is set in low screen ruling and a spatial frequency of the first achromatic image pattern is set in high screen ruling.