Color laser engraving and digital watermarking

• US 7,763,179 B2
• Filed: 12/19/2003
• Issued: 07/27/2010
• Est. Priority Date: 03/21/2003
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Levy, Kenneth L., Jones, Robert, LaBrec, Brian
• Primary Examiner(s): Ahmed; Shamim
• Assistant Examiner(s): Dahimene; Mahmoud
• Application Number:
  US10/742,510
• Publication Number:
  US 20050001419A1
• Time in Patent Office: 2,412 Days
• Field of Search: 216/94, 281/2, 283/113, 219/129
• US Class Current: 216/94
• CPC Class Codes: B41M 5/24 Ablative recording, e.g. by burning marks; Spark recording marking by high energetic means, e.g. by laser otherwise than burning or ablative removal B41M5/26; materials or methods for recording or reproduction by optical means G11B7/00
• CPC Class Codes: B41M 5/34 Multicolour thermography
• CPC Class Codes: B42D 2035/14 Dot or raster patterns
• CPC Class Codes: B42D 2035/24 Colours
• 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 25/324 Reliefs
• CPC Class Codes: B42D 25/333 Watermarks
• CPC Class Codes: B42D 25/346 Perforations
• CPC Class Codes: B42D 25/41 using electromagnetic radiation B42D25/435 takes precedence
• CPC Class Codes: B42D 25/435 using electromagnetic radiation, e.g. laser
• CPC Class Codes: G03C 11/02 Marking or applying text

Abstract

A color laser engraving method engraves a document including a surface layer and one or more sub-layers. The sub-layer includes different colors and orientations of ink. A laser provides openings in the surface layer—to expose color ink in the sub-layer—to create color images and/or text. The different orientations of the colored inks include, e.g., circular, linear and overlapped groupings of ink. A sub-layer preferably includes many repeated instances of the grouping. A digital watermark is embedded in a document via transfer of the digital watermark in an embedded image or text, or by pre-embedding the document via altering intensity of colored inks on the original document card stock. A digital watermark can be carried via modulation with a pseudo-random noise sequence.

Claims

1. A method of color laser exposing a document, the document comprising a multi-layer structure including a surface layer and one or more sub-layers, the one or more sub-layers including coloring, said method comprising:

receiving the document; and

selectively providing openings in the surface layer with a laser to expose one or more of the sub-layers, wherein the coloring is perceptible through the openings, and

wherein the laser is restricted so as to move only in a parallel manner relative to a surface of the document and in distance segments that correspond to sub-pixel and pixel sizes in the sub-layer, and wherein a location of the laser is used to choose an appropriate color channel, and a number of openings created for each pixel is used to represent intensity of a color channel.

2. A method of marking a document which is to receive laser engraving, said method comprising:

providing one or more sub-layers, the one or more sub-layers to include coloration;

providing variations in the coloration in terms of at least one of color intensity and color contrast, the variations conveying a machine-readable plural-bit message; and

arranging a surface layer over the one or more sub-layers, wherein the surface layer obscures the plural-bit message until laser engraving of at least a portion of the surface layer, after which the plural-bit message is machine-readable with optical scanning of the document.

3. The method of claim 2 wherein the plural-bit payload comprises a modulated pseudorandom noise sequence.

4. The method of claim 2, further comprising laser engraving the document, wherein the plural-bit message becomes machine-readable with analysis of optical scan data representing a document area that received the laser engraving.

5. The method of claim 4, wherein a laser used for laser engraving comprises a multi-nozzle laser.

6. The method of claim 5, where each of the nozzles comprises an optical fiber.

7. The method of claim 4, wherein a laser used for laser engraving comprises a diffraction grating.

8. The method of claim 2, wherein the machine-readable plural-bit message comprises a digital watermark component.

9. A method of providing a color image or pattern on media, the document comprising a multi-layer structure including a surface layer and one or more sub-layers, the one or more sub-layers including coloring, said method comprising:

receiving the document; and

selectively providing openings in the surface layer to expose one or more of the sub-layers, wherein the coloring is perceptible through the openings to provide the color image or pattern, wherein the openings are washed open after a curing process.