Method of detecting changes occurring in image editing using watermarks

• US 20030223099A1
• Filed: 05/29/2002
• Published: 12/04/2003
• Est. Priority Date: 05/29/2002
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Rolleston, Robert J., Fan, Zhigang, Cheng, Hui
• Granted Patent: US 6,954,541 B2
• Time in Patent Office: Days
• US Class Current: 358/537
• 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 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• 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 1/32144 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 1/32213 Modulating the least significant bits of pixels
• CPC Class Codes: H04N 1/32251 in multilevel data, e.g. greyscale or continuous tone data
• CPC Class Codes: H04N 1/32267 combined with processing of the image
• CPC Class Codes: H04N 1/32288 Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
• CPC Class Codes: H04N 1/32299 using more than one embedding method
• 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 2201/3242 of processing required or performed, e.g. for reproduction or before recording H04N2201/3256 and subgroups take precedence
• CPC Class Codes: H04N 2201/328 Processing of the additional information

Abstract

A method of editing a digital image having associated embedded data, such as printing hints, includes embedding a first watermark in the original image before the image is edited. The first watermarking scheme associates first watermark information with each pixel and is used to detect which pixels have been edited. A second watermark may be embedded in the original image according to a second watermarking scheme which associates second watermark information with non-overlapping groups of pixels in the original image. The second watermark information may be used to synchronize the first watermark information and to detect editing information which does not change pixel values. After editing, only those edited portions of the image need have their embedded data reapplied.

Claims

1. A method of editing a digital image having embedded data associated therewith, comprising:

embedding a first watermark in the original image according to a first watermarking scheme which associates first watermark information with each pixel in the original image;

editing the embedded image;

extracting the first watermark information from the edited embedded image to determine which pixels of the original image were edited;

regenerating the embedded data for those portions of the original image that were edited; and

associating the regenerating embedded data with those portions of the original image that were edited.

2. The method of claim 1, wherein the first watermark information comprises a code associated with each pixel'"'"'s color, such that if the pixel'"'"'s color is changed during editing, the code is changed.

3. The method of claim 1, wherein the first watermarking scheme comprises storing first watermark information associated with the pixel using at least one bit of the pixel'"'"'s color as defined in a color space.

4. The method of claim 3, wherein (i,j) is a location of a pixel in the original image and (L_i,j, a_i,j, b_i,j) is a color of the pixel in Lab color space;

and

wherein the first watermarking scheme comprises storing first watermark information associated with the pixel at location (i,j) using one bit of (a_i,j b_i,j).

5. The method of claim 4, wherein the first watermarking scheme comprises storing first watermark information associated with the pixel at location (i,j) using three bits of (a_i,j, b_i,j)

6. The method of claim 5, wherein the first watermarking scheme comprises using the least and second least significant bits in a* and the second least significant bit in b*.

7. The method of claim 1, further comprising:

partitioning the original image into a plurality of non-overlapping blocks of pixels;

embedding a second watermark in the original image according to a second watermarking scheme which associates second watermark information with each block of pixels in the original image;

extracting the second watermark information from the edited embedded image to determine which blocks of pixels were edited; and

using the extracted second watermark information to synchronize the first watermark information.

8. The method of claim 7, wherein the second watermark information comprises a unique code for each block of pixels for identifying if a block of pixels has been cropped or moved.

9. The method of claim 7, wherein the second watermarking scheme comprises storing second watermark information associated with the pixel using at least one bit of the pixel'"'"'s color.

10. The method of claim 7, wherein (i,j) is a location of a pixel in the original image, (L_i,j, a_i,j, b_i,j) is a color of the pixel, the plurality of blocks comprises pn×

qm and each pn×

qm block is assigned a unique block address.

11. The method of claim 10, further comprising:

for each n×

m block within the pn×

qm blocks, storing the unique block address in one of the bits of each of the nm pixel'"'"'s color.

13. The method of claim 7, wherein the embedded data comprises printing hints.

14. The method of claim 7, wherein the embedded data comprises digital rights data.

15. The method of claim 7, wherein the first watermark information comprises a code associated with each pixel'"'"'s color, such that if the pixel'"'"'s color is changed during editing, the code is changed;

and

wherein the second watermark information comprises a unique code for each block of pixels for identifying if a block of pixels has been cropped or moved.

16. The method of claim 7, wherein (i,j) is a location of a pixel in the original image, (L_i,j, a_i,j, b_i,j) is a color of the pixel and pn×

qm is the number of blocks of pixels;

wherein the first watermarking scheme comprises storing a first watermark associated with the pixel at location (i,j) using one bit of (a_i,j, b_i,j); and

wherein the second watermarking scheme comprises storing a second watermark for each n×

m block within the pn×

qm block using one bit of (a_i,j, b_i,j).

17. The method of claim 16, wherein the first watermarking scheme comprises storing the first watermark information in the least and second least significant bits in a* and the second least significant bit in b* and wherein the second watermarking scheme comprises storing the second watermark information in the least significant bit of b* of nm pixels.

18. The method of claim 1, further comprising editing the embedded data before re-associating it with those portions of the original image that were edited.

21. The method of claim 14, wherein the embedded data comprises digital rights data.

12. The method of claim 12, wherein the bit comprises the least significant bit of each pixel'"'"'s color.

19. A method of editing a digital image having embedded data associated therewith, comprising:

embedding a first watermark in the original image according to a first watermarking scheme which associates first watermark information with each pixel in the original image;

embedding a second watermark in the original image according to a second watermarking scheme which associates second watermark information with each non-overlapping group of pixels in the original image;

editing the embedded image;

extracting the first watermark information from the edited embedded image to determine which pixels of the original image were edited;

extracting the second watermark information from the edited image to determine which blocks of pixels were moved or cropped;

using the extracted second watermark information to determine which blocks of pixels were edited;

using the extracted first watermark information to synchronize the second watermark information; and

associating the embedded data with those portions of the original image that were edited, moved or cropped.

20. The method of claim 19, wherein the embedded data comprises printing hints.