Image processing apparatus, image forming apparatus, image processing system, and recording medium, for embedding digital watermark information in image data and controlling output of embedded digital watermark

An image processing apparatus, comprising:

• an image data generation unit configured to generate image data that includes a digital watermark, by embedding, in a least significant bit plane of original image data including a plurality of bit planes, at least one piece of digital watermark information and control information including both user-specific information for authenticating a user who requests output of said original image data and user-by-user digital watermark information indicating digital watermark information to be output on a user-by-user basis, and thereby generating image data that includes a digital watermark;
• and
• an output control unit configured to select said digital watermark information in accordance with said user based on said user-specific information and said user-by-user digital watermark information embedded in the image data, and combining a digital watermark based on the selected digital watermark information with said original image data for outputting,
• wherein
• said original image data is RGB data consisting of RGB color components;
• and
• said image data generation unit includes:
• a separating unit configured to separate said RGB data into a plurality of bit planes of each color component,
• a control information embedding unit configured to embed said control information to the least significant bit plane of any of R data, B data and G data, and
• a digital watermark embedding unit configured to embed said digital watermark information to the least significant bit plane of any of R data, B data and G data not having the control information embedded,
• wherein
• said at least one piece of digital watermark information includes a first piece of digital watermark information and a second piece of digital watermark information;
• and
• said digital watermark embedding unit includes:
• a first embedding unit configured to embed said first piece of digital watermark information into the least significant bit plane of any of R data, B data and G data not having the control information embedded, and
• a second embedding unit configured to embed said second piece of digital watermark information into the least significant bit plane of any of R data, B data and G data having neither the control information nor the first piece of digital watermark information embedded.