Information embedding apparatus, information embedding method, information extracting apparatus, information extracting method, computer program product

Abstract

A first-information obtaining unit that obtains first information and a second-information obtaining unit obtains second information. The second information has a higher degree of importance than that of the first information. A generating unit generates watermark image data including a group of first dot patterns including the first information and a group of second dot patterns including the first information and the second information and having a dot size enlarged from a dot size of the first dot patterns. A superposing unit superposes the generated watermark image data on a target image data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the configuration of an information embedding apparatus and an information extracting apparatus according to an embodiment;

FIG. 2 is a drawing illustrating an example of document image data to be printed;

FIG. 3A is a drawing of an example of 0 bit in a dot pattern for embedding first information;

FIG. 3B a drawing of an example of 1 bit in a dot pattern for embedding the first information;

FIG. 4 is a drawing of a disposition example of dot patterns of fine dots representing the first information disposed by a disposing unit of the information embedding apparatus according to the embodiment;

FIG. 5 is a drawing of a disposition example of dot patterns of fine dots and enlarged dots disposed by the disposing unit of the information embedding apparatus according to the embodiment;

FIG. 6 is a drawing of an example of document image data with a watermark superposed thereon by a superposing unit of the information embedding apparatus according to the embodiment;

FIG. 7 is a drawing of an example of watermark image data extracted from a watermark image extracting unit of the information extracting apparatus according to the embodiment, with dot patterns of a fine size not removed therefrom;

FIG. 8 is a drawing of an example of watermark image data extracted from the watermark image extracting unit of the information extracting apparatus according to the embodiment, with dot patterns of a fine size removed therefrom;

FIG. 9 is a drawing illustrating resolution conversion performed by a resolution converting unit of the information extracting apparatus according to the embodiment;

FIG. 10A is a drawing of a template representing a “0” bit for use in template matching by a second information extracting unit of the information extracting apparatus according to the embodiment;

FIG. 10B is a drawing of a template representing a “1” bit for use in template matching by a second information extracting unit of the information extracting apparatus according to the embodiment;

FIG. 11 is a flowchart of a procedure of processes from obtaining document image data at the information embedding apparatus according to the embodiment to printing the document image data with a watermark;

FIG. 12 is a flowchart of a procedure of processes from obtaining document image data at an information extracting apparatus 150 according to the embodiment to displaying the document image data and extracted information;

FIG. 13 is a flowchart of a procedure of processes when a first extracting scheme is used in which first information and second information are extracted at the information extracting apparatus 150 according to the embodiment;

FIG. 14 is a flowchart of a procedure of processes when a second extracting scheme is used in which second information is extracted at the information extracting apparatus 150 according to the embodiment; and

FIG. 15 is a drawing of a hardware configuration of a personal computer (PC) executing a program for achieving functions of the information embedding apparatus or the information extracting apparatus.

Claims

1. An information embedding apparatus comprising: an image obtaining unit to obtain image information;a first-information obtaining unit to obtain first information to be embedded in the image information obtained by the image obtaining unit;a second-information obtaining unit to obtain second information to be embedded in the image information obtained by the image obtaining unit, the second information having a higher degree of importance than that of the first information;a generating unit to generate watermark image information including a group of first image patterns including the first information and representing one bit or a plurality of bits and a group of second image patterns including the second information by using a dot size enlarged from the first image patterns; anda superposing unit to superpose the watermark image information on the image information obtained by the image obtaining unit thereby obtaining watermark-superposed image information.

2. The information embedding apparatus according to claim 1, wherein the generating unit includes: an area setting unit to set embedding areas obtained by dividing a display area of the image information obtained by the image obtaining unit in a predetermined size and an aggregated area formed of a plurality of adjacent ones of the embedding areas; anda disposing unit to dispose the second image patterns on one or more of the embedding areas selected according to a predetermined rule from the embedding areas forming the aggregated area set by the area setting unit and to dispose the first image pattern on one or more of the embedding areas not selected.

3. The information embedding apparatus according to claim 1, wherein the generating unit generates the watermark image information having the group of first image patterns and the group of the second image patterns in a plurality of types of dot pattern or line pattern.

4. The information embedding apparatus according to claim 1, wherein the generating unit generates the watermark image information having the group of first image patterns displayed in a dot size smaller than a dot size of a limit of an image reproduction capability of an image processing apparatus and the group of second image patterns displayed in a dot size larger than the dot size of the limit of the image reproduction capability of the image processing apparatus.

5. An information extracting apparatus comprising: an image obtaining unit to obtain watermark-superposed image information that is image information having superposed thereon watermark image information having a group of first image patterns representing one bit or a plurality of bits and a group of second image patterns with a dot size enlarged from a dot size of the first image patterns;a first-information extracting unit to extract first information embedded in the watermark-superposed image information from the group of the first image patterns and the group of the second image patterns of the watermark-superposed image information; anda second-information extracting unit to extract second information embedded in the watermark-superposed image information from the group of the second image patterns of the watermark-superposed image information.

6. The information extracting apparatus according to claim 5, further comprising a determining unit to determine whether the group of the first image patterns can be read from the watermark-superposed image information, wherein the first-information extracting unit does not extract the first information when it is determined by the determining unit that the group of the first image patterns cannot be read.

7. The information extracting apparatus according to claim 6, further comprising a resolution converting unit to convert the watermark-superposed image information to a predetermined resolution lower than a resolution of the image information, wherein the second-information extracting unit extracts the second information by performing template matching on the image information converted to the predetermined resolution by the resolution converting unit with third image patterns corresponding to the second image patterns with the predetermined resolution.

8. The information extracting apparatus according to claim 7, wherein the first-information extracting unit extracts the first information when it is determined by the determining unit that the first image patterns can be read, andthe second-information extracting unit specifies positions of aggregated blocks including bit information of the second information from positions of the first image patterns and the second image patterns specified by the first-information extracting unit at the time of extraction, and extracts information of one bit or a plurality of bits included in the second information for each aggregated block.

9. A method of embedding information comprising: obtaining image information;obtaining first information to be embedded in obtained image information;obtaining second information to be embedded in the obtained image information, the second information having a higher degree of importance than that of the first information;generating watermark image information including a group of first image patterns including the first information and representing one bit or a plurality of bits and a group of second image patterns including the second information by using a dot size enlarged from the first image patterns; andsuperposing the watermark image information on the obtained image information thereby obtaining watermark-superposed image information.

10. The method according to claim 9, wherein the generating includes: setting embedding areas obtained by dividing a display area of the obtained image information in a predetermined size and an aggregated area formed of a plurality of adjacent ones of the embedding areas; anddisposing the second image patterns on one or more of the embedding areas selected according to a predetermined rule from the embedding areas forming the aggregated area set at the setting and disposes the first image pattern on one or more of the embedding areas not selected.

11. The method according to claim 9, wherein the generating includes generating the watermark image information formed of the group of first image patterns and the group of the second image patterns in a plurality of types of dot pattern or line pattern.

12. The method according to claim 9, wherein the generating includes generating the watermark image information formed of the group of first image patterns displayed in a dot size smaller than a dot size of a limit of an image reproduction capability of an image processing apparatus and the group of second image patterns displayed in a dot size larger than the dot size of the limit of the image reproduction capability of the image processing apparatus.

13. The method according to claim 9, further comprising performing a printing process on the watermark-superposed image information.

14. The method according to claim 9, wherein the obtaining includes obtaining the image information by scanning a paper document.

15. A method of extracting information comprising: obtaining watermark-superposed image information that is image information having superposed thereon watermark image information formed of a group of first image patterns representing one bit or a plurality of bits and a group of second image patterns with a dot size enlarged from a dot size of the first image patterns;extracting first information embedded in the watermark-superposed image information from the group of the first image patterns and the group of the second image patterns of the watermark-superposed image information; andextracting second information embedded in the watermark-superposed image information from the group of the second image patterns of the watermark-superposed image information.

16. The method according to claim 15, further comprising determining whether the group of the first image patterns can be read from the watermark-superposed image information, wherein the extracting first information includes not extracting the first information when it is determined at the determining that the group of the first image patterns cannot be read.

17. The method according to claim 16, further comprising converting the watermark-superposed image information to a predetermined resolution lower than a resolution of the image information, wherein the extracting second information includes extracting the second information by performing template matching on the image information converted to the predetermined resolution at the converting with third image patterns corresponding to the second image patterns with the predetermined resolution.

18. The method according to claim 17, wherein the extracting first information includes extracting the first information when it is determined at the determining that the first image patterns can be read, andthe extracting second information includes specifying positions of aggregated blocks including bit information of the second information from positions of the first image patterns and the second image patterns specified at the first information extracting at the time of extraction, and extracts information of one bit or a plurality of bits included in the second information for each aggregated block.

19. A computer program product to store therein a computer program codes which when executed on a computer causes the computer to perform the method according to claim 9.

20. A computer program product to store therein a computer program codes which when executed on a computer causes the computer to perform the method according to claim 15.