Watermarking a page description language file

• US 20050286948A1
• Filed: 05/31/2005
• Published: 12/29/2005
• Est. Priority Date: 01/30/2002
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Walton, Scott E.
• Granted Patent: US 8,228,563 B2
• Time in Patent Office: Days
• US Class Current: 400/62
• 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 1/32267 combined with processing of the image
• CPC Class Codes: H04N 2201/0067 Converting to still picture data
• CPC Class Codes: H04N 2201/0068 Converting from still picture data
• CPC Class Codes: H04N 2201/3271 Printing or stamping

Abstract

The present invention provides methods and systems for steganographically encoding a file which is in a page description language (PDL) such as PostScript. Aspects of the present invention can be used to: i) encode a PDL file and generate an encoded PDL file; and ii) provide an “interpreter” which generates raster images from a PDL file. Portions of the raster images can be steganographically encoded. Encoded raster images can be printed or the raster images can be combined into a new PDL file.

Claims

1. A method of digital watermarking a file which is in a page description language (PDL) comprising:

interpreting a PDL file;

generating a set of raster images;

digital watermarking the set of raster images; and

printing said raster images.

2. The method recited in claim 1 wherein said PDL comprises PostScript.

3. The method recited in claim 1 wherein a mask is used to determine areas of the set of raster images that are to be digital watermarked.

4. The method recited in claim 1 wherein the interpreting utilizes a Ghostscript interpreter.

5. The method recited in claim 2 wherein the interpreting utilizes a Ghostscript interpreter.

6. The method recited in claim 3 wherein the interpreting utilizes a Ghostscript interpreter.

7. A system for watermarking a file which is represented in a page description language (PDL), said method comprising:

an interpreter to interpret a PDL file and to generate a plurality of raster images;

a watermarking program to digital watermark the plurality of raster images; and

a printer to print the watermarked raster images.

8. The system recited in claim 7 wherein the PDL comprises PostScript.

9. The system recited in claim 7 wherein a mask is used to determine which areas of the plurality of raster images are to be watermarked.

10. A method of steganographically encoding a file which is represented in a page description language (PDL), said method comprising:

providing a set of raster images representing at least a portion of the file;

providing a mask which will guide steganographic encoding of at least some of the set of raster images;

steganographic encoding at least some of the set of raster images according to the mask;

providing the steganographic encoded set of raster images.