Watermarked image generator and method of embedding watermarks into an input image

• US 7,006,256 B2
• Filed: 01/16/2002
• Issued: 02/28/2006
• Est. Priority Date: 01/16/2002
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Wang, Shen-ge, Lin, Ying-wei, Fan, Zhigang, Cheng, Hui
• Primary Examiner(s): Patel, Kanjibhai
• Assistant Examiner(s): Tabatabai, Abolfazl
• Application Number:
  US09/683,540
• Publication Number:
  US 20030133163A1
• Time in Patent Office: 1,504 Days
• Field of Search: 382/100, 382/232, 358/3.28, 358/3.3, 358/534, 713/176, 713/179, 283/72, 283 74- 81, 283/85.93, 283/113, 283/901, 283/902, 283/85, 283/93, 386/94, 380/51, 380/54, 380/210, 380/252, 380/287
• US Class Current: 358/3.28
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• 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: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32256 in halftone data
• CPC Class Codes: H04N 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes

Abstract

A watermarked image generator includes a watermark data source that inputs watermark data to a watermark embedding device. The watermark embedding device halftones the input image to generate the output image made of 2×2 binary patterns, the 2×2 binary patterns forming the watermarks embedded in the output image. The watermark embedding device includes a tri-level error diffusion generator that performs tri-level error diffusion on the input image by halftoning the input image into black, white and 50% gray. A plurality of halftoning circuits successively replace each pixel of the halftoned input image with one of a plurality of the 2×2 binary patterns. The one of the plurality of 2×2 binary patterns corresponds to at least one respective bit of the watermark data when a pixel of the halftoned image data is 50% gray. The watermark data can be segmentation map data of the input image.

Claims

1. A watermarked image generator that embeds watermarks into an input image to generate a watermarked output image, comprising:

a watermark data source that inputs watermark data to a watermark embedding device, the watermark embedding device halftoning the input image to generate the output image made of 2×

2 binary patterns, the 2×

2 binary patterns forming the watermarks embedded in the output image,

wherein the watermark embedding device includes;

a tri-level error diffusion generator that performs tri-level error diffusion on a reduced resolution version of the input image by halftoning the input image into black, white and 50% gray; and

a plurality of halftoning circuits that successively replace each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns, the one of the plurality of 2×

2 binary patterns being selected based on at least one bit of the watermark data when a pixel of the halftoned image data is 50% gray.

2. The watermarked image generator according to claim 1, wherein, when a pixel of the halftoned image data is white, the one of the plurality of 2×

2 binary patterns forms an all white pattern.

3. The watermarked image generator according to claim 1, wherein, when a pixel of the halftoned image data is black, the one of the plurality of 2×

2 binary patterns forms an all black pattern.

4. The watermarked image generator according to claim 1, wherein the watermark data is binary data, and, when a pixel of the halftoned image data is 50% gray, the one of the 2×

2 binary patterns forms one of a plurality of polarized patterns, the one of the plurality of polarized patterns is polarized according to the status of the at least one bit of the binary data.

5. The watermarked image generator according to claim 1, wherein the one of the plurality of 2×

2 binary patterns is selected based on two bits of the watermark data when a pixel of the halftoned image is 50% gray.

6. The watermarked image generator according to claim 5, wherein the watermark data is binary data, and, when a pixel of the halftoned image data is 50% gray, the one of the 2×

2 binary patterns forms one of a plurality of polarized patterns, the one of the plurality of polarized patterns is polarized according to the values of each of the two bits of the binary data.

7. The watermarked image generator according to claim 1, wherein the watermark data is segmentation values of each pixel of the halftoned input image, and, when a pixel of the halftoned input image data is 50% gray, the one of the 2×

2 binary patterns forms one of a plurality of polarized patterns, the one of the plurality of polarized patterns is polarized according to the segmentation value for that pixel.

8. The watermarked image generator according to claim 1, wherein the input image is a continuous tone input image.

9. A method of embedding watermarks received from a watermark data source into an input image to generate a watermarked halftone output image, comprising:

halftoning the input image by performing tri-level error diffusion on a reduced resolution version of the input image by halftoning the input image into black, white and 50% gray; and

successively replacing each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns to generate the output image made of 2×

2 binary patterns, the 2×

2 binary patterns forming the watermarks embedded in the output image, the one of the plurality of 2×

2 binary patterns selected being based on at least one bit of the watermark data when a pixel of the halftoned image data is 50% gray.

10. The method according to claim 9, wherein successively replacing each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns comprises replacing each white pixel of the halftoned image data with one of the plurality of 2×

2 binary patterns forming an all white pattern.

11. The method according to claim 9, wherein successively replacing each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns comprises replacing each black pixel of the halftoned image data with one of the plurality of 2×

2 binary patterns forming an all black pattern.

12. The method according to claim 9, wherein:

the watermark data is binary data; and

successively replacing each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns comprises replacing each 50% gray pixel of the halftoned image data with one of a plurality of polarized 2×

2 binary patterns, the one of the plurality of polarized 2×

2 binary patterns being polarized according to a value of the at least one bit of the binary data.

13. The method according to claim 9, wherein the one of the plurality of 2×

2 binary patterns corresponds to two bits of the watermark data when a pixel of the halftoned image is 50% gray.

14. The method according to claim 13, wherein:

the watermark data is binary data; and

successively replacing each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns comprises replacing each 50% gray pixel of the halftoned image data with one of a plurality of polarized 2×

2 binary patterns, the one of the plurality of polarized 2×

2 binary patterns being polarized according to a value of two bits of the binary data.

15. The method according to claim 9, wherein:

the watermark data is segmentation values of each pixel of the halftoned input image; and

successively replacing each pixel of the halftoned input image with one of a plurality of the 2×

2 binary patterns comprises replacing each 50% gray pixel of the halftoned image data with one of a plurality of polarized 2×

2 binary patterns, the one of the plurality of polarized 2×

2 binary patterns being polarized according to a segmentation value.

16. The method according to claim 9, wherein the input image is a continuous tone input image and the tri-level error diffusion is performed on the continuous tone input image.