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US 8,009,893 B2Granted
Security document carrying machine readable pattern
AssigneeDigimarc Corporation
InventorsGeoffrey B. Rhoads, Tony F. Rodriguez
Life of this patent
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AssigneeDigimarc Corporation
InventorsGeoffrey B. Rhoads, Tony F. Rodriguez
Estimating the term…
The present invention relates generally to security documents (e.g., banknotes, ID documents, certificates, packaging, etc.). One claim recites a security document including a security pattern provided thereon. The security pattern includes a line structure in which lines width or line spacing is adjusted to convey a predefined, machine-readable pattern in a frequency transform domain. Another claim recites a security document including a security pattern provided thereon. The security pattern is provided in the security document through modifications to a color provided on the security document. The security pattern conveys a predefined, machine-readable pattern in a frequency transform domain. Of course, additional combinations and claims are provided as well.
A security document comprising:
A security document comprising:
A security document comprising:
A security document comprising:
An apparatus comprising:
An apparatus comprising:
An apparatus comprising:
An apparatus comprising:
A non-transitory computer-readable storage medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:
A non-transitory computer-readable storage medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:
A method comprising:
A method comprising:
Dependencies are inferred from the claim text.
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Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title: embedded in the image data, i.e.…
Robust watermarking, e.g. average attack or collusion attack resistant: geometric transfor invariant watermarking, e.g. affine transform invariant
Methods relating to embedding, encoding, decoding, detection or retrieval operations: spatial or amplitude domain methods
Methods relating to embedding, encoding, decoding, detection or retrieval operations: in colour image data
Term ended 8 May 2015 (estimated)
The invention relates to methods and systems for carrying auxiliary data in graphical structures on printed documents.
Digital watermarking (sometimes termed “data hiding” or “data embedding”) is a growing field of endeavor, with several different approaches. The present assignee's work is reflected in the patents and applications detailed above, together with laid-open PCT application WO97/43736. Other work is illustrated by U.S. Pat. Nos. 5,734,752, 5,646,997, 5,659,726, 5,664,018, 5,671,277, 5,687,191, 5,687,236, 5,689,587, 5,568,570, 5,572,247, 5,574,962, 5,579,124, 5,581,500, 5,613,004, 5,629,770, 5,461,426, 5,743,631, 5,488,664, 5,530,759, 5,539,735, 4,943,973, 5,337,361, 5,404,160, 5,404,377, 5,315,098, 5,319,735, 5,337,362, 4,972,471, 5,161,210, 5,243,423, 5,091,966, 5,113,437, 4,939,515, 5,374,976, 4,855,827, 4,876,617, 4,939,515, 4,963,998, 4,969,041, and published foreign applications WO 98/02864, EP 822,550, WO 97/39410, WO 96/36163, GB 2,196,167, EP 777,197, EP 736,860, EP 705,025, EP 766,468, EP 782,322, WO 95/20291, WO 96/26494, WO 96/36935, WO 96/42151, WO 97/22206, WO 97/26733. Some of the foregoing patents relate to visible watermarking techniques. Other visible watermarking techniques (e.g. data glyphs) are described in U.S. Pat. Nos. 5,706,364, 5,689,620, 5,684,885, 5,680,223, 5,668,636, 5,640,647, 5,594,809.
Much of the work in data embedding is not in the patent literature but rather is published in technical articles. In addition to the patentees of the foregoing patents, some of the other workers in this field (whose watermark-related writings can by found by an author search in the INSPEC or NEXIS databases, among others) include I. Pitas, Eckhard Koch, Jian Zhao, Norishige Morimoto, Laurence Boney, Kineo Matsui, A. Z. Tirkel, Fred Mintzer, B. Macq, Ahmed H. Tewfik, Frederic Jordan, Naohisa Komatsu, Joseph O'Ruanaidh, Neil Johnson, Ingemar Cox, Minerva Yeung, and Lawrence O'Gorman.
FIGS. 1A and 1B show prior art techniques for achieving grey-scale effects using line art.
FIG. 2 shows a virtual array of grid points that can be imposed on a security document image according to an embodiment.
FIG. 3 shows a virtual array of regions that can be imposed on a security document image according to the FIG. 2 embodiment.
By way of introduction, this specification begins with review of techniques for embedding watermark data in line art, as disclosed in my application Ser. No. 09/074,034.
Referring to FIG. 2, the earlier-described technique employs a grid 10 of imaginary reference points arrayed over a line art image. The spacing between points is 250 microns in the illustrated arrangement, but greater or lesser spacings can of course be used.
Associated with each grid point is a surrounding region 12, shown in FIG. 3. As described below, the luminosity (or reflectance) of each of these regions 12 is slightly changed to effect subliminal encoding of binary data.