1. An image processing apparatus comprising: a first input unit, arranged to input image information; a recognizing unit, arranged to recognize a plurality of text regions included in the input image information; a generator, arranged to generate authentication information corresponding to each text region to control processing for the text region; a setting unit, arranged to set whether text in each text region is to be visible or not after the processing for the text region is performed; an embedding unit, arranged to embed the authentication information corresponding to each text region into the respective corresponding text region as a digital watermark, wherein the digital watermark is visible when the visible text is set for the corresponding text region and, is invisible when the invisible text is set for the corresponding text region, wherein said image processing apparatus comprises a processor configured to function as at least said recognizing unit and said generator.