Image processing techniques for printing identification cards and documents

• US 20040074973A1
• Filed: 04/09/2003
• Published: 04/22/2004
• Est. Priority Date: 04/09/2002
• Status: Active Grant

• Current Assignee: L-1 Secure Credentialing, LLC (Advent International Corporation)
• Original Assignee: L-1 Secure Credentialing, LLC (Advent International Corporation)
• Inventors: Jones, Robert, Bi, Daoshen, Duggan, Charles F., Schneck, Nelson
• Granted Patent: US 7,815,124 B2
• Time in Patent Office: Days
• US Class Current: 235/488
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/23 Identity cards
• CPC Class Codes: B42D 25/309 Photographs
• CPC Class Codes: B42D 25/333 Watermarks
• CPC Class Codes: B42D 25/382 absorbing or reflecting infrared light
• CPC Class Codes: B42D 25/387 absorbing or reflecting ultraviolet light
• CPC Class Codes: B42D 25/41 using electromagnetic radiation B42D25/435 takes precedence
• CPC Class Codes: B42D 25/42 by photographic processes
• CPC Class Codes: H04N 1/32133 on the same paper sheet, e.g. a facsimile page header
• 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 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3236 Details of authentication information generation
• 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

Abstract

The invention relates to identification documents, and in particular to pre-printing processing covert images, such as UV or IR images, provided on such identification documents. In one implementation, the invention provides a method of processing a digital image that is to be printed on a surface of an identification document as a fluorescing-capable image to improve the quality of the image. Edges or boundaries are detected within the image, the detected edges or boundaries forming an intermediate image. The edges or boundaries within the image are emphasized, and the emphasized image is used for printing the covert image. In some implementations of the invention, a digital watermark is embedded in the covert image.

Claims

1. A method of processing a digital image that is to be printed on a surface of an identification document as a covert image, comprising:

detecting at least one of edges and boundaries within the image, the detected edges or boundaries forming an intermediate image; and

emphasizing the edges or boundaries within the intermediate image.

2. The method of claim 1, wherein emphasizing further comprises iteratively copying the intermediate image onto itself, wherein each iterative copy is offset with respect to the original intermediate image.

3. The method of claim 2, wherein the offset comprises a range of 2-5 pixels.

4. The method of claim 1, wherein emphasizing comprises growing the edges or boundaries by a predetermined thickness.

5. The method of claim 1, wherein detecting edges comprises generating a horizontal edge image comprising horizontal edge components and generating a vertical edge image comprising vertical edge components.

6. The method of claim 5, further comprising summing the horizontal edge image and the vertical edge image, the sum comprising the intermediate image.

7. The method of claim 6, wherein emphasizing comprises iteratively pasting copies of the horizontal edge image and vertical edge image onto the intermediate image, wherein each iteratively pasted horizontal edge image and each vertical edge image is offset with respect to a first placed horizontal edge image and a first placed vertical edge image, respectively.

8. The method of claim 1, further comprising increasing the contrast in the image prior to detecting the at least one of edges and boundaries within the image.

9. The method of claim 1, further comprising printing the emphasized image in a covert medium on an identification document.

10. The method of claim 9, wherein the covert medium comprises at least one of an ultraviolet printing medium, an infrared printing medium, a thermachromic printing medium, a ferrofluidic printing medium, and an optically variable printing medium.

11. The method of claim 9, wherein prior to printing, the emphasized intermediate image is converted to a bitonal image.

12. The method of claim 11 further comprising inverting the image prior to printing.

13. The method of claim 12, further comprising printing the inverted bitonal image as a covert image on an identification document.

14. A method of providing a covert image to an identification document, comprising:

increasing contrast in at least a portion of a digital image;

dithering the contrast-increased portion of the digital image; and

transferring the dithered image to the identification document.

15. The method of claim 14 further comprising, prior to increasing contrast, detecting at least one of edges and boundaries within the digital image, the at least one of detected edges and boundaries comprising the portion of the digital image that has had its contrast increased.

16. The method of claim 14 wherein the covert image, once transferred to the identification document, is generally visibly perceptible only when exposed to a stimulus adapted to enable the covert image to be viewed by a human eye.

17. The method of claim 14 wherein transferring the dithered image to the identification document comprises printing the dithered image on the identification document using a covert medium, the covert medium comprising at least one of an ultraviolet printing medium, an infrared printing medium, a thermachromic printing medium, a ferrofluidic printing medium, and an optically variable printing medium.

18. A method to reduce at least one of image washout and blurring caused by the fluorescence of a covert image that is to be transferred to an identification document, said method comprising, prior to the transfer of the covert image:

receiving a digital image that is to be used as a model to generate the covert image;

increasing contrast in the digital image;

detecting edges or boundaries within the image, the detected edges or boundaries forming an intermediate image; and

emphasizing the edges or boundaries within the intermediate image.

19. The method of claim 18, wherein emphasizing comprises iteratively copying the intermediate image onto itself, wherein each iterative copy is offset with respect to the original intermediate image.

20. The method of claim 19, wherein the offset a range of 2-5 pixels.

21. The method of claim 18, wherein emphasizing comprises growing at least one of the edges and boundaries by a predetermined thickness.

22. The method of claim 18, wherein detecting edges comprises generating a horizontal edge image comprising horizontal edge components and generating a vertical edge image comprising vertical edge components.

23. The method of claim 19, further comprising the step of summing the horizontal edge image and the vertical edge image, the sum comprising the intermediate image.

24. The method of claim 18, wherein emphasizing step comprises iteratively pasting copies of the horizontal edge image and vertical edge image onto the intermediate image, wherein each iteratively pasted horizontal edge image and each vertical edge image is offset with respect to a first placed horizontal edge image and a first placed vertical edge image, respectively.

25. The method of claim 18, further comprising converting the emphasized intermediate image to a bitonal image and inverting the bitonal image.

26. The method of claim 25, further comprising printing the inverted bitonal image on the identification document with at least one covert medium.

27. An identification document comprising:

a core layer comprising a core material capable of having printed thereon an image formed using a covert medium;

a covert image printed to the core layer, the covert image formed by;

providing a digital image that is to be used as a model to generate the covert image;

increasing the contrast in the digital image;

detecting edges or boundaries within the digital image, the detected edges or boundaries forming an intermediate image;

emphasizing the edges or boundaries within the intermediate image; and

printing the emphasized intermediate image in a covert medium on the core layer.

31. The identification document of claim 27, wherein said covert image comprises steganographic encoding.

32. The identification document of claim 31, wherein the steganographic encoding comprises a digital watermark.

28. An identification document, comprising:

a core layer comprising a core material capable of having printed thereon an image formed using a covert medium;

a covert image printed to the core layer, the covert image formed by;

providing a digital image that is to be used as a model to generate the covert image;

increasing contrast in at least a portion of the digital image;

dithering the contrast-increased portion of the digital image; and

transferring the dithered image to the identification document.

29. The identification document of claim 28, wherein said covert image comprises steganographic encoding.

30. The identification document of claim 29, wherein the steganographic encoding comprises a digital watermark.

33. The identification document of claim 29, wherein the core comprise at least one of Teslin, polycarbonate, PVC, and a plastic.

34. A method of producing an identification document comprising:

receiving a digital image;

processing the digital image to emphasize a set of image features; and

printing the processed digital image on the identification document using at least one covert printing medium, the covert printing medium being visible to a human eye only upon application of a predetermined stimulus.

35. The method of claim 34, wherein the processing helps alleviate at least one of image blurring and washout of the digital image printed with the covert printing medium.

36. The method of claim 34, wherein the sets of image features comprise at least one of eyes, mouth edges, face outline, ears and hair outline.