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Optical watermark

A watermarking and document technology, applied in printing, printing devices, image data processing, etc., can solve the problems of counterfeit display, inability to provide sufficient protection, etc., and achieve the effect of high security and increased complexity

Inactive Publication Date: 2004-10-06
TRUSTCOPY PTE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is also in a single layer, and is rather simple and does not provide sufficient protection, such as forging display

Method used

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Embodiment Construction

[0026] Such as figure 1 As shown, the optical watermark in the present invention has a multi-layer structure. Watermark layers are layered on top of each other to provide multiple layers as well as classes of protection. The stacking of several layers means that deriving structural parameters and hidden information from optical watermarking alone is nearly impossible, if not difficult.

[0027] Each watermark layer is a lattice of repeating structures. The latent image object is embedded in the watermark layer by modulation. This may include, for example, phase modulation. In optical watermarking the structures and orientations of the different watermark layers must be different from each other. Only the decoder corresponding to a specific watermark layer can be used to observe the latent image object embedded in the specific watermark layer.

[0028] Basic watermark layer - 2-D dot matrix

[0029] The basic watermarking layer is a 2-D lattice that varies in two orthog...

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PUM

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Abstract

A multiple layered watermark is generated to be placed on document, to protect against counterfeiting and forgery. Hidden information embedded into each of the watermark's layers is only detectable by using a corresponding decoder. Because of the multiple-layered structure, it is difficult to reverse engineer the optical watermark. The generalized watermark structure significantly increases the "key space" of the decoder.

Description

technical field [0001] The invention relates to a method and apparatus for producing optical watermarks on printed and electronic documents. Background technique [0002] Throughout this specification or related references, documents should be understood to include: printed documents and / or electronic documents and / or copies of printed documents (printed or electronic) and / or copies of electronic documents ( printed or electronic), and includes those documents that contain text, images, graphics, video, photographs, and other media representations. [0003] The structure of a watermark (also called a carrier dot pattern) is a repeating pattern with the simplest and most basic as a two-dimensional ("2-D") dot matrix. The complexity of the dot pattern structure determines the level of security. Embedding the latent image object into the watermark is carried out by modulating the latent image object on the dot pattern. Use the decoder to observe the latent image demodulation...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B41J29/00G06T1/00H04N1/387
CPCG06T1/0071G06T2201/0051
Inventor 黄晟吴健康
Owner TRUSTCOPY PTE