| 摘要 |
PURPOSE:To make the delation of a mark difficult, and to improve the reliability of security protection by automatically changing the color of character pattern information in accordance with a position on the pattern concerned or a position on an input image. CONSTITUTION:A first gamma correction circuit 310 corrects gray balance of input image information outputted from an image scanner 100. A delay circuit 320 delays an output of the image information in order to fit a timing of the image information to a delay of detection in a mark area detecting circuit. A masking circuit 330 converts color image information of three colors of R, G and B to color image information of four colors of C, M, Y and BK(black), and a second gamma correction circuit 340 executes a gradation correction corresponding to a recording characteristic of a color printer 200. A mark information generating circuit 370 outputs a prescribed character pattern being additional information to a mark information synthesizing circuit at a prescribed timing. In such a way, it is difficult to erase the additional information, and reliability of security protection can be enhanced. |
