1. An image processing apparatus comprising: a generating section for generating watermark data associated with a chromatic or achromatic watermark for copy control, which appears as a result of making a copy; a composing section for generating composite image data associated with an image composed by joining an original image with a watermark for copy control, on a basis of the watermark data generated by the generating section and original image data obtained by reading an original document; and a determinating section for determining whether the original document includes a chromatic color or not, on a basis of the original image data, wherein the composing section generates composite image data on a basis of generated watermark data and the original image data when the determinating section determines that the original document includes a chromatic color, wherein the composing section generates composite image data on a basis of generated achromatic watermark data and the original image data when the determinating section determines that the original document does not include a chromatic color.