Image forming apparatus and density adjusting method

A density adjustment, image technology, applied in image communication, electrography, optics, etc., can solve the problems of unlawful copying, undetectable, and invisible characters.
CN101212535AInactive Publication Date: 2008-07-02KYOCERA DOCUMENT SOLUTIONS INC
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
KYOCERA DOCUMENT SOLUTIONS INC
Publication Date
2008-07-02
Estimated Expiration
Not applicable · inactive patent

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Abstract

The present invention provides an image forming apparatus and a density adjustment method for forming a latent image portion and a background portion on an original that cannot be known to exist, and when copying, display characters for preventing illegal output, etc. Furthermore, it is possible to reliably detect the special dot pattern formed on the background portion, so that unauthorized copying can be prohibited. The control unit detects a plurality of background part densities and a plurality of latent image part densities from an image obtained by an image reading operation on the paper on which a sample image is formed, and selects only one of the detected background part densities. When copying an original image with a dot pattern in the background, the density of the background portion of the dot pattern can be detected, and from the detected densities of the latent image portion, only the original image with the latent image portion can be extracted. The latent image density of the dot image corresponding to the dots constituting the latent image portion is formed on the copy, and the extracted background portion density and the latent image portion density matching the background portion density are derived.
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Description

technical field

[0001] The present invention relates to a technology for preventing important materials such as confidential documents from being leaked or falsified due to unauthorized copying. Background technique

[0002] Conventionally, image forming apparatuses such as digital multi-function peripherals and copiers and image reading apparatuses have been required to have functions such as preventing unauthorized reading or outputting. In particular, leakage of confidential information to the outside due to unauthorized reading of confidential documents has become a serious problem in companies, and technology that can reliably prevent and limit reading of confidential documents has been urgently desired.

[0003] In response to such requirements and wishes, for example, Japanese Patent Laying-Open No. 2005-094327 and Japanese Patent Laid-Open No. 2005-236954 disclose using the characteristics of scanners and printers to make text appear on the background when copying or...

Claims

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