A security document comprising artwork including a security pattern, characterized in that the security pattern has the form of a line structure in which lines width or line spacing is adjusted to carry predefined data. The artwork is generated by the modifying at least one color of at least a part of the artwork to embed the security pattern in the artwork. Methods for detecting the security pattern include use of a frequency domain structure to detect the security pattern despite rotation and scaling of the document, use of signal tiling to improve signal detection, and use of statistical analyses to verify detection of the security pattern.

 
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< Apparatus and method for image forming

> Data carrier, method for the production thereof and gravure printing plate

> Method of watermark with hybrid halftone dots

~ 00530