1. An image processing apparatus comprising: a pattern adder configured to add a set of third dot patterns to a second region of an image, where an output of the image is inhibited based on the set of third dot patterns to be detected from the image to which the set of third dot patterns is added; a watermark generator configured to generate, in a first region of the image, a first watermark for copy control which includes a first illegal copy warning dot pattern and a first background dot pattern where the first illegal copy warning dot pattern becomes invisible as a result of making a copy; a determiner configured to determine whether or not the pattern adder adds the set of third dot patterns to the image, when the first watermark for copy control generated by the watermark generator is added to the image; and a region setter configured to set the second region of the image where the set of third dot patterns is to appear, when the determiner determines that the set of third dot patterns is to be added to the image; wherein at least part of the second region does not overlap with the first region, such that the set of third dot patterns appears at a different portion of the image from where the first illegal copy warning dot pattern appears.