Information embedding method, apparatus and recording medium

• US 6,591,009 B1
• Filed: 07/28/1999
• Issued: 07/08/2003
• Est. Priority Date: 07/28/1998
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Yoda, Akira, Usami, Yoshinori
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): Kassa, Yosef
• Application Number:
  US09/362,368
• Time in Patent Office: 1,441 Days
• Field of Search: 382/167, 382/166, 382/164, 382/232, 382/233, 382/248, 382/249, 382/251, 382/100, 382/219, 382/234, 382/181, 382/196, 358/518, 358/520, 358/523, 358/538, 380/51, 380/54, 380/210, 380/252, 380/287, 380/201, 713/176, 713/179
• US Class Current: 382/165
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: H04N 1/32267 combined with processing of the image
• CPC Class Codes: H04N 1/32309 in colour image data

Abstract

To deeply encrypt and embed auxiliary information into image data, table generation means generates a table, based on a quantization error which occurs when image data S0 is converted from a first color space, to which the image data S0 belongs, to a second color space that is a destination of conversion. The table represents which color coordinate of a second color space a color coordinate of a first color space is mapped onto. In coding means, information H0 to be embedded is coded by referring to the table, whereby coded auxiliary information H1 is obtained. When the image data S0 is converted in color conversion means, the auxiliary information H1 is embedded into the quantization error, whereby image data S1 embedded with the auxiliary information H1 is obtained.

Claims

1. An information embedding method of deeply encrypting and embedding into image data auxiliary information related to said image data, said information embedding method comprising the steps of:

when an image is converted from a first color space, to which said image belongs, to a second color space having a color reproduction characteristic differing from said first color space,

selecting a single second conversion table from a plurality of second conversion tables for each of a plurality of pieces of auxiliary information,

calculating a quantization error in converting said image data to said second color space, based on a difference in color reproduction characteristic between said first and second color spaces; and

encrypting and embedding said auxiliary information by switching a first conversion table and said selected second conversion table in accordance with a position on said image represented by said image data into said quantization error.

2. The information embedding method as set forth in claim 1, wherein a difference in gamut between said first color space and said second color space is decided, and for a color space inside a gamut in both color spaces, a geometrical error, which occurs when a color coordinate in said first color space is converted to a corresponding color coordinate in said second color space, is calculated as said quantization error.

3. The information embedding method as set forth in claim 1, wherein a difference in gamut between said first color space and said second color space is decided, a color space in said second color space outside the gamut of said first color space is compressed inside the gamut of said first color space, and an error occurring by the compression is calculated as said quantization error.

4. The information embedding method as set forth in claim 1, wherein said auxiliary information is embedded into said quantization error in a space where a quantization resolution of said first color space shrinks.

5. The information embedding method as set forth in claim 1, wherein said auxiliary information is embedded into said quantization error in a space where a quantization resolution of said first color space increases.

6. The information embedding method as set forth in claim 1, wherein

said first conversion table is for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said selected second conversion table is for converting a predetermined color coordinate in said first color space to a different color coordinate adjacent to a color coordinate in said second color space corresponding to said predetermined color coordinate.

7. An auxiliary information reading method of reading out auxiliary information from image data embedded with said auxiliary information by the information embedding method as set forth in claim 6, said auxiliary information reading method comprising the steps of:

converting said image data by said first conversion table and obtaining first image data; and

reading out said auxiliary information, based on a difference in color between the image data embedded with said auxiliary information and said first image data.

8. An image output method of outputting image data embedded with said auxiliary information by the information embedding method as set forth in claim 6, said image output method comprising the steps of:

reading out said auxiliary information from said image data; and

performing a process based on said auxiliary information with respect to said image data and outputting said image data.

9. The image output method as set forth in claim 8, wherein said image data is given said auxiliary information so that said auxiliary information can be recognized visually and is output.

10. A computer readable recording medium having recorded a program for causing a computer to execute a method of reading out auxiliary information from image data embedded with said auxiliary information by the information embedding method as set forth in claim 6, said program comprising the procedures of:

converting said image data by said first conversion table and obtaining first image data; and

reading out said auxiliary information, based on a difference in color between the image data embedded with said auxiliary information and said first image data.

11. A computer readable recording medium having recorded a program for causing a computer to execute an image output method of outputting image data embedded with auxiliary information by the information embedding method as set forth in claim 6, said program comprising the procedures of:

reading out said auxiliary information from said image data; and

performing a process based on said auxiliary information with respect to said image data and outputting said image data.

12. The computer readable recording medium as set forth in claim 11, wherein said outputting procedure is a procedure of giving said auxiliary information to said image so that said auxiliary information can be recognized visually and outputting said image data.

13. The information embedding method as set forth in claim 1, wherein

said first conversion table is for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said plurality of second conversion tables are for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates, said plurality of second conversion tables corresponding in number to said plurality of predetermined color coordinates.

14. The information embedding method as set forth in claim 1, wherein

said first conversion table is for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and a plurality of second conversion tables are for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates, said plurality of second conversion tables corresponding in number to said plurality of predetermined color coordinates.

15. The information embedding method as set forth in claim 14, wherein said plurality of different pieces of auxiliary information include partition information for partitioning positions at which said plurality of pieces of auxiliary information are embedded.

16. The information embedding method as set forth in claim 1, wherein

said first conversion table is for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said selected second conversion table is for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates.

17. An information embedding apparatus for deeply encrypting and embedding into image data auxiliary information related to said image data, said information embedding apparatus comprising:

when an image is converted from a first color space, to which said image belongs, to a second color space having a color reproduction characteristic differing from said first color space, a single second conversion table is selected from a plurality of second conversion tables for each of a plurality of pieces of auxiliary information,

quantization error calculation means for calculating a quantization error in converting said image data to said second color space, based on a difference in color reproduction characteristic between said first and second color spaces; and

embedment means for encrypting and embedding said auxiliary information by switching a first conversion table and said selected second conversion table in accordance with a position on said image represented by said image data into said quantization error.

18. The information embedding apparatus as set forth in claim 17, wherein said quantization error calculation means is further provided with decision means for deciding a difference in gamut between said first color space and said second color space and is means for calculating a geometrical error, which occurs when a color coordinate in said first color space is converted to a corresponding color coordinate in said second color space, as said quantization error, for a color space inside a gamut in both color spaces.

19. The information embedding apparatus as set forth in claim 17, wherein said quantization error calculation means is further provided with decision means for deciding a difference in gamut between said first color space and said second color space and is means for compressing a color space in said second color space, which is outside the gamut of said first color space, inside the gamut of said first color space and for calculating an error, which occurs by the compression, as said quantization error.

20. The information embedding apparatus as set forth in claim 17, wherein said embedment means is means for embedding said auxiliary information into a quantization error in a space where a quantization resolution of said first color space shrinks.

21. The information embedding apparatus as set forth in claim 17, wherein said embedment means is means for embedding said auxiliary information into a quantization error in a space where a quantization resolution of said first color space increases.

22. The information embedding apparatus as set forth in claim 17, wherein

said quantization error calculation means is provided with means for generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said selected second conversion table for converting a predetermined color coordinate in said first color space to a different color coordinate adjacent to a color coordinate in said second color space corresponding to said predetermined color coordinate; and

said embedment means is means for embedding said auxiliary information by switching said first conversion table and said selected second conversion table in accordance with a position on said image represented by said image data, when said image data is converted from said first color space to said second color space.

23. An auxiliary information reading apparatus for reading out auxiliary information from image data embedded with said auxiliary information by the information embedding apparatus as set forth in claim 22, said auxiliary information reading apparatus comprising:

conversion means for converting said image data by said first conversion table and obtaining first image data; and

read means for reading out said auxiliary information, based on a difference in color between the image data embedded with said auxiliary information and said first image data.

24. An image output apparatus for outputting image data embedded with said auxiliary information by the information embedding apparatus as set forth in claim 22, said image output apparatus comprising:

read means for reading out said auxiliary information from said image data; and

output means for performing a process based on said auxiliary information with respect to said image data and outputting said image data.

25. The image output apparatus as set forth in claim 24, wherein said output means is means for giving said auxiliary information to said image so that said auxiliary information can be recognized visually and outputting said image data.

26. The information embedding apparatus as set forth in claim 17, wherein

said quantization error calculation means is provided with means for generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said plurality of second conversion tables for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates, said plurality of second conversion tables corresponding in number to said plurality of predetermined color coordinates;

and

said embedment means is means for selecting said single second conversion table from said plurality of second conversion tables in accordance with a content of said auxiliary information and embedding said auxiliary information by switching said first conversion table and said selected second conversion table in accordance with a position on said image represented by said image data, when said image data is converted from said first color space to said second color space.

27. The information embedding apparatus as set forth in claim 17, wherein

said quantization error calculation means is provided with means for generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said plurality of second conversion tables for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates, said plurality of second conversion tables corresponding in number to said plurality of predetermined color coordinates;

and

said embedment means is means for selecting said single second conversion table from said plurality of second conversion tables for each of a plurality of pieces of auxiliary information and embedding a plurality of different pieces of auxiliary information by switching said first conversion table and said selected second conversion table in accordance with a position on said image represented by said image data while selecting said single second conversion table for each said auxiliary information, when said image data is converted from said first color space to said second color space.

28. The information embedding apparatus as set forth in claim 27, wherein said plurality of different pieces of auxiliary information include partition information for partitioning positions at which said plurality of pieces of auxiliary information are embedded.

29. The information embedding apparatus as set forth in claim 17, wherein

said quantization error calculation means is provided with means for generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said selected second conversion table for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates;

and

said embedment means is means for embedding a plurality of different pieces of auxiliary information for each said color coordinate by switching said first conversion table and said second conversion table in accordance with a color coordinate on said image represented by said image data, when said image data is converted from said first color space to said second color space.

30. A computer readable recording medium having recorded a program for causing a computer to execute an information embedding method of deeply encrypting and embedding into image data auxiliary information related to said image data, said program comprising the procedures of:

when an image is converted from a first color space, to which said image belongs, to a second color space having a color reproduction characteristic differing from said first color space,

selecting a single second conversion table from a plurality of second conversion tables for each of a plurality of pieces of auxiliary information,

calculating a quantization error in converting said image data to said second color space, based on a difference in color reproduction characteristic between said first and second color spaces; and

encrypting and embedding said auxiliary information by switching a first conversion table and said selected second conversion table in accordance with a position on said image represented by said image data into said quantization error.

31. The computer readable recording medium as set forth in claim 30, wherein said quantization error calculating procedure further has a procedure of deciding a difference in gamut between said first color space and said second color space and is a procedure of calculating a geometrical error, which occurs when a color coordinate in said first color space is converted to a corresponding color coordinate in said second color space, as said quantization error, for a color space inside a gamut in both color spaces.

32. The computer readable recording medium as set forth in claim 30, wherein said quantization error calculating procedure further has a procedure of deciding a difference in gamut between said first color space and said second color space and is a procedure of compressing a color space in said second color space, which is outside the gamut of said first color space, inside the gamut of said first color space and of calculating an error, which occurs by the compression, as said quantization error.

33. The computer readable recording medium as set forth in claim 30, wherein said embedding procedure is a procedure of embedding said auxiliary information into said quantization error in a space where a quantization resolution of said first color space shrinks.

34. The computer readable recording medium as set forth in claim 30, wherein said embedding procedure is a procedure of embedding said auxiliary information into said quantization error in a space where a quantization resolution of said first color space increases.

35. The computer readable recording medium as set forth in claim 30, wherein

said quantization error calculating procedure has a procedure of generating a first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and a second conversion table for converting a predetermined color coordinate in said first color space to a different color coordinate adjacent to a color coordinate in said second color space corresponding to said predetermined color coordinate.

36. The computer readable recording medium as set forth in claim 30, wherein

said quantization error calculating procedure has a procedure of generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said plurality of second conversion tables for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates, said plurality of second conversion tables corresponding in number to said plurality of predetermined color coordinates.

37. The computer readable recording medium as set forth in claim 30, wherein

said quantization error calculating procedure has a procedure of generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said plurality of second conversion tables for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates, said plurality of second conversion tables corresponding in number to said plurality of predetermined color coordinates.

38. The computer readable recording medium as set forth in claim 37, wherein said plurality of different pieces of auxiliary information include partition information for partitioning positions at which said plurality of pieces of auxiliary information are embedded.

39. The computer readable recording medium as set forth in claim 30, wherein

said quantization error calculating procedure has a procedure of generating said first conversion table for converting a color coordinate in said first color space to a corresponding color coordinate in said second color space and said selected second conversion table for converting a plurality of predetermined color coordinates in said first color space to different color coordinates adjacent to color coordinates in said second color space respectively corresponding to said plurality of predetermined color coordinates.