Digital watermark detection using predetermined color projections

• US 7,995,790 B2
• Filed: 06/28/2006
• Issued: 08/09/2011
• Est. Priority Date: 01/26/2001
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Hannigan, Brett T., Reed, Alastair M.
• Primary Examiner(s): Le; Brian Q
• Application Number:
  US11/427,265
• Publication Number:
  US 20070147653A1
• Time in Patent Office: 1,868 Days
• Field of Search: 382/100, 382/232, 380/210, 380/252, 380/287, 380/54, 713/176, 400/460, 386/94, 399/366, 283/902, 358/3.28
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/0042 Fragile watermarking, e.g. so as to detect tampering
• 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

Abstract

The present invention relates to digital watermarking. In one implementation, a system is provided to read a digital watermark from digital imagery which includes data representing a number of pixels. Each pixel of the number of pixels is defined by a set of values representing color components of the particular pixel. The digital watermark is embedded in the digital imagery through modifications to at least some data representing the digital imagery. The system includes a filter to calculate values of pixels along a preferred projection axis, the preferred projection axis corresponds to a direction of embedding determined based on color characteristics of at least some pixels associated with the digital imagery; and a digital watermark reader which operates on values calculated by the filter. Other implementations are provided as well.

Claims

1. A system to read a digital watermark from digital imagery that includes data representing a number of pixels, wherein each pixel of the number of pixels is defined by a set of values representing color components of the particular pixel, and wherein the digital watermark is embedded in the digital imagery through modifications to at least some data representing the digital imagery, the system comprising:

a filter for calculating values of pixels along a preferred projection axis, wherein the preferred projection axis corresponds to a direction of embedding determined based on color characteristics of at least some pixels associated with the digital imagery; and

an electronic processing unit programmed as a digital watermark reader for operating on values calculated by the filter.

2. The system recited in claim 1 wherein the filter examines pixels in a neighborhood of pixels surrounding one or more of the pixels to determine the preferred projection axis.

3. The system recited in claim 2 wherein the digital watermark includes a spatial pattern of a predetermined size and wherein the filter examines pixels in an area of the spatial pattern to determine the preferred projection axis.

8. The system of claim 1 wherein the digital watermark reader comprises an electronic processing unit programmed to read digital watermarks.

17. The system of claim 1 wherein the filter comprises an electronic processing unit programmed for calculating values of pixels along a preferred projection axis.

4. A method of reading a digital watermark from a color image that includes a plurality of pixels and that was digital watermarked using a scale to black digital watermarking technique, the method comprising:

filtering the color image to generate filtered data by projecting color values of a set of pixels onto a selected axis that is determined by examining color of surrounding pixels—

and not through filtering with a predetermined process without an examination of the color values; and

using a programmed electronic processing unit, reading the watermark from resulting filtered data.

9. A non-transitory computer readable medium comprising non-transitory instructions stored thereon to cause an electronic processing unit to perform the method of claim 4.

13. An electronic system programmed to perform the method of claim 4.

5. A method of reading a digital watermark from a digital image or video that includes a plurality of pixels, wherein each pixel of the plurality of pixels is defined by a set of numbers representing color components, the method comprising:

filtering the set of numbers that represents each pixel by projecting the set of numbers to a selected axis, wherein a direction of the selected axis is determined by examining color values of pixels in an area associated with each pixel, and wherein the filtering provides results; and

using a programmed electronic processing unit, reading a digital watermark from the results provided by the filtering.

6. The method recited in claim 5 wherein the filtering determines the direction of the selected axis for each pixel by examining values of pixels in a neighborhood of pixels surrounding each pixel.

10. A non-transitory computer readable medium comprising non-transitory instructions stored thereon to cause an electronic processing unit to perform the method of claim 5.

11. A non-transitory computer readable medium comprising non-transitory instructions stored thereon to cause an electronic processing unit to perform the method of claim 6.

14. An electronic system programmed to perform the method of claim 5.

15. An electronic system programmed to perform the method of claim 6.

7. A method of reading a digital watermark that has embedded as one or more luminance values of at least some pixels of an image or video by projecting color changes representing the digital watermark onto a luminance axis of each of the some pixels, the method comprising:

filtering the image prior to reading the digital watermark by first projecting color values of each pixel onto a preferred projection axis that is determined by examining color values of predetermined pixels, wherein at least the values are used to determine a direction of the axis; and

using a programmed electronic processing unit, reading the watermark from data associated with a result of the filtering.

12. A non-transitory computer readable medium comprising non-transitory instructions stored thereon to cause an electronic processing unit to perform the method of claim 7.

16. An electronic system programmed to perform the method of claim 7.

18. A system to read a digital watermark from digital imagery that includes data representing a number of pixels, wherein each pixel of the number of pixels is defined by a set of values representing color components of the particular pixel, and wherein the digital watermark is embedded in the digital imagery through modifications to at least some data representing the digital imagery, the system comprising:

means for calculating values of pixels along a preferred projection axis, wherein the preferred projection axis corresponds to a direction of embedding determined based on color characteristics of at least some pixels associated with the digital imagery; and

means for reading digital watermarking from values calculated by the filter.

19. The system recited in claim 18 wherein the means for calculating examines pixels in a neighborhood of pixels surrounding one or more of the pixels to determine the preferred projection axis.

20. The system recited in claim 18 wherein the digital watermark includes a spatial pattern of a predetermined size and wherein the means for calculating examines pixels in an area of the spatial pattern to determine the preferred projection axis.