Water-mark embedding method and system

• US 6,728,408 B1
• Filed: 09/01/1998
• Issued: 04/27/2004
• Est. Priority Date: 09/03/1997
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshiura, Hiroshi, Takeuchi, Toshifumi, Arai, Takao, Nakamura, Masafumi, Echizen, Isao
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Dang, Duy M.
• Application Number:
  US09/144,467
• Time in Patent Office: 2,065 Days
• Field of Search: 382/100, 382/232, 382/238, 382/135, 382/282, 382/284, 382/294, 382/233, 382/154, 382/275, 382/289, 382/295, 382/296, 380/200, 380/34, 380/51, 380/201, 380/252, 380/287, 380/210, 345/419, 345/629, 345/634, 235/469, 707/104.1, 713/129, 713/126
• US Class Current: 382/232
• CPC Class Codes: G06T 1/0021 Image 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 1/32229 with selective or adaptive application of the additional information, e.g. in selected regions of the image H04N1/32213 takes precedence
• CPC Class Codes: H04N 1/32251 in multilevel data, e.g. greyscale or continuous tone 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 data embedding method and apparatus and a data reproducing method and apparatus are provided which can apply a digital watermark to various contents. Instead of embedding watermarking information in respective pixels or by using a relation between pixels, the watermarking information is embedded as a position pattern of changed pixels in the contents. Reliability comparable with conventional techniques can be obtained irrespective of a change in a smaller number of pixels for the contents.

Claims

1. A data embedding method of embedding watermarking data x in a two-dimensional image having m horizontal pixels and n vertical pixels, comprising the steps of:

selecting two-dimensional partial images based on the watermarking data x, the two-dimensional partial image having k horizontal pixels (k×

i=m, where k, i and m are positive integers) and l vertical pixels (l×

j=n, where l, j and n are positive integers),

wherein said two-dimensional partial images are selected from the two-dimensional image based on watermarking information to be embedded in the two-dimensional image so that positional relation between said selected two-dimensional partial images forms the watermarking information; and

changing a value of each pixel of the selected two-dimensional partial image such that an arithmetic operation value of pixel values of the selected two-dimensional partial image takes a specific value to generate digital watermarks, thereby distinguishing the selected two-dimensional partial images from the other two-dimensional partial images not selected.

2. A recording medium storing a moving image embedded with the watermarking data x by the data embedding method according to claim 1 and compressed.

3. A data reproducing method comprising the steps of:

detecting the two-dimensional partial image whose pixel values were changed, the two-dimensional partial image corresponding to the watermarking data x embedded by the data embedding method according to claim 1;

storing information concerning the position of the two-dimensional partial image of the two-dimensional image detected by said detecting step in storage means; and

detecting a pattern of the position information of the two-dimensional partial image stored in the storage means to reproduce the watermarking data x corresponding to said detected pattern.

4. A data reproducing method according to claim 3, where said pattern detecting step comprises detecting an interval between two-dimensional partial image images stored in said storage means to convert said interval between two-dimensional partial images into the watermarking data x.

5. A data reproducing system comprising:

two-dimensional partial image detecting means for detecting the two-dimensional partial image whose pixel values were changed, the two-dimensional partial image corresponding to the watermarking data x embedded by the data embedding method according to claim 1;

storing means for storing position information of the two-dimensional partial image of the two-dimensional image detected by said detecting step; and

pattern detecting means for detecting a pattern of the position information of the two-dimensional partial image stored in the storage means.

6. A data embedding method according to claim 1, wherein said selecting step comprises converting said embedded data x into an interval between two-dimensional partial images to select the two-dimensional partial image whose pixel values are to be changed so as to be disposed at said interval between two-dimensional partial images.

7. A data embedding method according to claim 1, wherein said operation value is sum value.

8. A data embedding system for embedding watermarking data x in a two-dimensional image having m horizontal pixels and n vertical pixels, comprising:

selecting means for selecting two-dimensional partial images based on the watermarking data x, the two-dimensional partial image having k horizontal pixels (k xi=m, k, i and m are positive integers) and e vertical pixels (l×

j=n, e, j and n are positive integers),

wherein said two-dimensional partial images are selected from the two-dimensional image based on watermarking information to be embedded in the two-dimensional image so that positional relation between said selected two-dimensional partial images forms the watermarking information; and

pixel value changing means coupled to said selecting means for changing a value of each pixel of the selected two-dimensional partial image such that an arithmetic operation value of pixel values of the selected two-dimensional partial image takes a specific value to generate digital watermarks, thereby distinguishing the selected two-dimensional partial images from the other two-dimensional partial images not selected.

9. A data embedding method according to claim 8, wherein said operation value is a sum value.

10. A method of embedding watermarking information in two dimensional image data, comprising the steps of:

dividing the two-dimensional image data into a plurality of blocks;

selecting a partial set of blocks based on the watermarking information from a plurality of divided blocks,

wherein said partial set of blocks are selected from the two-dimensional image data based on said watermarking information to be embedded in the two-dimensional image data so that positional relation between said selected partial set of blocks forms the watermarking information; and

changing arithmetic values of image data in a block of the selected partial set of blocks so as to satisfy a particular condition to generate digital watermarks, thereby distinguishing said selected partial set of blocks from other partial sets of blocks.

11. A method according to claim 10, wherein the block is a two-dimensional partial image constituting a compression processing unit.

12. A method according to claim 10, wherein the block is a two-dimensional partial image, and the values of image data are a sum of luminances of pixels in each block.

13. A method according to claim 10, wherein the partial set of blocks corresponding to the watermarking information is selected depending upon the watermarking information and random integers.

14. A method of embedding watermarking information in two dimensional image data, comprising the steps of:

dividing the two-dimensional image data into a plurality of blocks;

selecting a partial set of blocks based on the watermarking information from a plurality of divided blocks,

wherein said partial set of blocks are selected from the two-dimensional image data based on said watermarking information to be embedded in the two-dimensional image data so as to form a pattern corresponding to the watermarking information; and

changing arithmetic values of image data in a block of the selected partial set of blocks so as to satisfy a particular condition to thereby generate digital watermarks,

wherein the partial set of blocks is selected so as not to duplicate blocks between types of the watermarking information, if A is N/M or smaller where A is the number of types of the watermarking information, N is a total sum of blocks, and M is the number of partial sets (macro blocks) of blocks and N and M are positive integers.

15. A method of embedding watermarking information in two dimensional image data, comprising the steps of:

dividing the two-dimensional image data into a plurality of blocks;

selecting a partial set of blocks based on the watermarking information from a plurality of divided blocks,

wherein said partial set of blocks are selected from the two-dimensional image data based on said watermarking information to be embedded in the two-dimensional image data so as to form a pattern corresponding to the watermarking information; and

changing arithmetic values of image data in a block of the selected partial set of blocks so as to satisfy a particular condition to thereby generate digital watermarks,

wherein the partial set of blocks is selected so as to duplicate blocks between types of the watermarking information, a difference of duplicated block numbers between arbitrary two partial sets of blocks being set to 0 or 1, if A larger than N/N where A is the number of types of the watermarking information, N is a total sum of blocks, and M is the number of partial sets (macro blocks) of blocks and N, M are positive integers.

16. A method of reading watermarking information embedded in two-dimensional image data, comprising the steps of:

dividing the two-dimensional image data into a plurality of blocks;

storing partial sets of blocks in correspondence with each type of the watermark information;

judging whether a value of image data of each block satisfies a specific condition;

comparing sets of blocks satisfying the specific condition with the partial sets of blocks and selecting a partial set of blocks having the number of blocks common in both the set of blocks and the partial set of blocks larger than a predetermined value; and

judging information corresponding to the selected partial set of blocks as the watermarking information,

wherein the watermarking information has been embedded into the two-dimensional image by selecting a partial set of blocks based on the watermarking information, and

wherein partial set of blocks is selected from the two-dimensional image data so as to form a pattern corresponding to the watermarking information to be embedded into the two-dimensional data.

17. A method according to claim 16, wherein the two-dimensional image data is compressed image data, and whether the value of image data of each block satisfies the specific condition is judged from a correspondence between a value of compressed data and a value of image data.

18. A system for embedding watermarking information in two-dimensional image data, comprising:

means for dividing the two-dimensional image data into a plurality of blocks;

means for selecting a partial set of blocks based on the watermarking information from a plurality of divided blocks and changing arithmetic values of image data in a block of the selected partial set of blocks so as to satisfy a particular condition to thereby generate digital watermarks,

wherein said partial set of blocks are selected from the two-dimensional image data based on said watermarking information to be embedded in the two-dimensional image data so that positional relation between said selected partial set of blocks forms the watermarking information.

19. A system according to claim 18, wherein the block is a two-dimensional partial image constituting a compression processing unit.

20. A system according to claim 18, wherein the block is a two-dimensional partial image, and the values of image data are a sum of luminances of pixels in each block.

21. A method according to claim 18, wherein the partial set of blocks corresponding to the watermarking information is selected depending upon the watermarking information and random integers.

22. A system for embedding watermarking information in two-dimensional image data, comprising:

means for dividing the two-dimensional image data into a plurality of blocks;

means for selecting a partial set of blocks based on the watermarking information from a plurality of divided blocks and changing arithmetic values of image data in a block of the selected partial set of blocks so as to satisfy a particular condition to thereby generate digital watermarks,

wherein said partial set of blocks are selected from the two-dimensional image data based on said watermarking information to be embedded in the two-dimensional image data so as to form a pattern corresponding to the watermarking information,

wherein the partial set of blocks is selected so as not to duplicate blocks between types of the watermarking information, if A is N/N or smaller where A is the number of types of the watermarking information, N is a total sum of blocks, and N is the number of partial sets (macro blocks) of blocks and N and N are positive integers.

23. A system for embedding watermarking information in two-dimensional image data, comprising:

means for dividing the two-dimensional image data into a plurality of blocks;

means for selecting a partial set of blocks based on the watermarking information from a plurality of divided blocks and changing arithmetic values of image data in a block of the selected partial set of blocks so as to satisfy a particular condition to thereby generate digital watermarks,

wherein said partial set of blocks are selected from the two-dimensional image data based on said watermarking information to be embedded in the two-dimensional image data so as to form a pattern corresponding to the watermarking information, and

wherein the partial set of blocks is selected so as to duplicate blocks between types of the watermarking information, a difference of duplicated block numbers between arbitrary two partial sets of blocks being set to 0 or 1, if A larger than N/N where A is the number of types of the watermarking information, N is a total sum of blocks, and N is the number of partial sets (macro blocks) of blocks and N and N are positive integers.

24. A system for reading watermarking information embedded in two-dimensional image data, comprising:

means for dividing the two-dimensional image data into a plurality of blocks;

means for storing partial sets of blocks in correspondence with each type of the watermark information;

means for judging whether a value of image data of each block satisfies a specific condition;

means for comparing sets of blocks satisfying the specific condition with the partial sets of blocks and selecting a partial set of blocks having the number of blocks common in both the set of blocks and the partial set of blocks larger than a predetermined value; and

means for judging information corresponding to the selected partial set of blocks as the watermarking information,

wherein the watermarking information has been embedded into the two-dimensional image by selecting a partial set of blocks based on the watermarking information, and

wherein partial set of blocks is selected from the two-dimensional image data so as to form a pattern corresponding to the watermarking information to be embedded into the two-dimensional data.

25. A system according to claim 24, wherein the two-dimensional image data is compressed image data, and whether the value of image data of each block satisfies the specific condition is judged from a correspondence between a value of compressed data and a value of image data.