Methods and systems for watermark processing of line art images

• US 6,449,377 B1
• Filed: 05/06/1998
• Issued: 09/10/2002
• Est. Priority Date: 05/08/1995
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US09/074,034
• Time in Patent Office: 1,588 Days
• Field of Search: 382/232, 382/233, 382/234, 382/235, 382/236, 382/237, 382/238, 382/100, 382/135, 380/210, 380/287, 380/54, D19/11, 283/72, 283/85, 283/93, 283/113, 283/57, 283/901, 283/902
• US Class Current: 382/100
• CPC Class Codes: B29C 45/1418 the inserts being deformed or preformed, e.g. by the injection pressure
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection
• CPC Class Codes: G07D 7/0034 using watermarks
• CPC Class Codes: G07D 7/004 using digital security elements, e.g. information coded on a magnetic thread or strip
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00005 relating to image data
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00092 relating to the original or to the reproducing medium, e.g. imperfections or dirt detecting properties of a sheet H04N1/00681
• CPC Class Codes: H04N 1/00244 with a server, e.g. an internet server fax-servers or the like for store and forward H04N1/324
• CPC Class Codes: H04N 1/00846 based on detection of a dedicated indication, e.g. marks or the like
• CPC Class Codes: H04N 1/00859 Issuing an alarm or the like
• CPC Class Codes: H04N 1/00867 : with additional data, e.g. by adding a warning message details of embedding additional information in an image H04N1/32144
• CPC Class Codes: H04N 1/0087 : with hidden additional data, e.g. data invisible to the human eye
• CPC Class Codes: H04N 1/00875 : Inhibiting reproduction, e.g. by disabling reading or reproduction apparatus
• CPC Class Codes: H04N 1/32144 : embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32203 : Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 : involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32219 : involving changing the position of selected pixels, e.g. word shifting, or involving modulating the size of image components, e.g. of characters H04N1/32224 takes precedence
• CPC Class Codes: H04N 1/32261 : in binary data H04N1/32256 takes precedence
• CPC Class Codes: H04N 1/32304 : Embedding different sets of additional information
• CPC Class Codes: H04N 1/32309 : in colour image data
• CPC Class Codes: H04N 2201/3205 : of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 : of an address
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3239 : using a plurality of different authentication information
• CPC Class Codes: H04N 2201/3246 : of data relating to permitted access or usage, e.g. level of access or usage parameters for digital rights management [DRM] related to still images
• CPC Class Codes: H04N 2201/3249 : data relating to a linked page or object, e.g. hyperlink
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: Y10S 283/901 : Concealed data

Abstract

Line art on banknotes and the like is subtly altered to steganographically encode plural-bit digital information. For example, the lines'"'"' widths or spacings can be locally changed so as to slightly modulate the apparent luminance of the document. The encoded information can be decoded using suitably-equipped processing equipment and used to identify a document as a banknote. Various anti-counterfeiting actions can then be taken.

Claims

1. A method of embedding binary data in a banknote, comprising:

providing nominal line art for the banknote;

defining a plurality of virtual regions in at least an excerpt of said line art, each of said regions having an area less than 0.001 square inches; and

changing a luminance value of plural of said regions to embed binary data therein,

wherein said changes are not apparent to a human viewer of the banknote, yet can be detected from visible light scan data corresponding to said banknote.

2. The method of claim 1 further comprising changing said luminance by modulating the width of plural lines in said line art.

3. The method of claim 1 further comprising changing said luminance by modulating the position of plural lines in said line art.

4. The method of claim 1 further comprising changing said luminance by inserting new lines in said line art.

5. A banknote produced by the process of claim 1.

6. A method for encoding plural-bit digital data in a banknote, to facilitate later machine identification of the banknote, comprising:

receiving initial banknote artwork including plural artwork elements;

changing the position o r dimension of certain of said artwork elements to steganographically encode said plural-bit digital data, yielding adjusted banknote artwork; and

printing a banknote corresponding to said adjusted banknote artwork.

7. The method of claim 6 in which the initial banknote artwork includes line art, and the method includes slightly changing the positions of lines comprising said artwork to encode said plural-bit data.

8. The method of claim 7 that includes, for at least one line, changing its position in a first direction at a first region therealong, and changing its position in a second direction different than the first at a second region therealong.

9. The method of claim 6 in which the banknote artwork includes line art, and the method includes slightly changing the widths of lines comprising said artwork to encode said plural-bit data.

10. The method of claim 9, that includes, for at least one line, increasing its width in a first region, and decreasing its width in a second region.

11. The method of claim 6 that includes:

defining an array of regions spanning at least an excerpt of the initial banknote artwork; and

changing the artwork within plural of said regions to either increase or decrease the respective luminance of each.

12. The method of claim 11 in which the defining includes imposing a virtual grid over said excerpt.

13. The method of claim 6 that includes adjusting said initial artwork by inserting one or more new lines therein.

14. A banknote produced by the method of claim 6.

15. A method of watermarking a banknote to convey auxiliary data, the banknote including an element having a contour, characterized in that the method includes spatially shifting the location of said contour.