Image processor and image processing method

• US 6,741,758 B2
• Filed: 04/04/2001
• Issued: 05/25/2004
• Est. Priority Date: 04/07/2000
• Status: Expired due to Fees

• Current Assignee: Canon Inc.
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ishida, Yoshihiro, Hayashi, Junichi, Iwamura, Keiichi
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US09/824,745
• Publication Number:
  US 20010055390A1
• Time in Patent Office: 1,147 Days
• Field of Search: 382/100, 382/232, 382/248, 382/250, 382/276, 382/277, 382/279, 382/287, 382/294, 382/302, 358/3.28, 358/3.3, 380/54, 380/220, 713/176
• US Class Current: 382/294
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: H04N 1/32154 Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/3216 using Fourier transforms
• CPC Class Codes: H04N 1/32277 Compression
• CPC Class Codes: H04N 1/32309 in colour image data
• CPC Class Codes: H04N 1/32352 Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers for decoding, detection or retrieval operations H04N1/32149 and subgroups take precedence
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• 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
• CPC Class Codes: H04N 2201/3283 Compression

Abstract

A registration signal embedding method of embedding registration signals adaptively in accordance with image signals. The frequency property of image data is determined, and either a first registration signal or a second registration signal is selected in accordance with the frequency property, and is added to image data. The registration embedded in this way has the advantage of increased resistance and easy detection.

Claims

1. An image processing method of embedding registration signals in image data, comprising:

a feature component detecting step of detecting a feature component of said image data;

a registration signal selecting step of selecting one registration signal from a plurality of registration signals, in accordance with said feature component; and

an adding step of adding to said image data the registration signal selected by said registration signal selecting step.

2. The image processing method according to claim 1,

wherein said feature component detecting step further comprises a frequency property determining step of determining frequency properties of said image data.

3. The image processing method according to claim 1, further comprising:

a frequency transforming step of transforming said image data into frequency components; and

an inverse frequency transforming step of transforming said frequency components into spatial components.

4. The image processing method according to claim 3,

wherein in said frequency transforming step, Fourier transformation is performed to transform said image data into amplitude spectra.

5. The image processing method according to claim 1,

wherein in said frequency property determining step, determination is made using frequency components of said image data.

6. The image processing method according to claim 1, further comprising:

a block dividing step of dividing said image data into at least one blocks; and

a block synthesizing step of combining blocks divided by said block dividing step to reconstruct the image.

7. The image processing method according to claim 1,

wherein said plurality of registration signals has impulses in frequency components different from one another.

8. The image processing method according to claim 1,

wherein in said registration signal selecting step, a registration signal having impulses in low frequency components is selected from said plurality of registration signals for image data with a smaller number of high frequency components, and a registration signal having impulses in high frequency components is selected from said plurality of registration signals for image data with a larger number of high frequency components.

9. The image processing method according to claim 1,

wherein said feature component is an edge component.

10. The image processing method according to claim 1,

wherein said plurality of registration signals have one period.

11. The image processing method according to claim 1,

wherein said plurality of registration signals include first and second registration signals, and

in said registration signal selecting step, the first registration signal is selected in said edge component and the second registration signal is selected in components other than said edge component.

12. The image processing method according to claim 11,

wherein said second registration signal is smaller in amplitude than said first registration signal.

13. An image processing method of inputting image data with registration signals embedded therein, subjected to geometric transformation, and extracting registration signals from said inputted image data to perform registration processing, comprising:

a registration signal extracting step of extracting registration signals from said image data;

a frequency property determining step of determining frequency properties of said image data;

a geometric transformation identifying step of identifying geometric transformation to which said image data is subjected, using said extracted registration signals and determination results of said determination in the frequency property determining step; and

a geometric transforming step of performing inverse transformation of said identified geometric transformation.

14. The image processing according to claim 13, further comprising:

a frequency transforming step of transforming said image data into frequency components; and

an inverse frequency transforming step of transforming said frequency components into spatial components.

15. The image processing method according to claim 13,

wherein in said frequency property determining step, determination is made using frequency components of said image data.

16. The image processing method according to claim 13,

wherein in said frequency transforming step, Fourier transformation is performed, and conversion into amplitude spectra as said frequency components is made.

17. The image processing method according to claim 13, further comprising:

a block dividing step of dividing said image data into at least one blocks; and

a block synthesizing step of combining blocks divided by said block dividing step to reconstruct the image.

18. The image processing method according to claim 13,

wherein said geometric transformation is scaling.

19. An image processor for embedding registration signals in image data, comprising:

feature component detecting means for detecting a feature component of said image data;

registration signal selecting means for selecting one registration signal from a plurality of registration signals, in accordance with said feature component; and

adding means for adding to said image data the registration signal selected by said registration signal selecting means.

20. An image processor for inputting image data with registration signals embedded therein, subjected to geometric transformation, and extracting registration signals from said inputted image data to perform registration processing, comprising:

registration signal extracting means for extracting registration signals from said image data;

frequency property determining means for determining frequency properties of said image data;

geometric transformation identifying means for identifying geometric transformation to which said image data is subjected, using said extracted registration signals and determination results of said determination by the frequency property determining means; and

geometric transforming means for performing inverse transformation of said identified geometric transformation.

21. A computer program product embodying a program for implementing an image processing method of embedding registration signals in image data,

the program comprising:

program codes for the feature component detecting step of detecting a feature component of said image data;

program codes for a registration signal selecting step of selecting one registration signal from a plurality of registration signals, in accordance with said feature component; and

program codes for an adding step of adding to said image data the registration signal selected by said registration signal selecting step.

22. A computer data signal embodied in a propagating wave and used for implementing an image processing method of embedding registration signals in image data, comprising:

code signals for use in a feature component detecting step of detecting a feature component of said image data;

code signals for use in a registration signal selecting step of selecting one registration signal from a plurality of registration signals, in accordance with said feature component; and

code signals for use in an adding step of adding to said image data the registration signal selected by said registration signal selecting step.

23. A computer program product embodying a program for implementing an image processing method of inputting image data with registration signals embedded therein, subjected to geometric transformation, and extracting registration signals from said inputted image data to perform registration processing,

the program comprising:

program codes for a registration signal extracting step of extracting registration signals from said image data;

program codes for a frequency property determining step of determining frequency properties of said image data;

program codes for a geometric transformation identifying step of identifying geometric transformation to which said image data is subjected, using said extracted registration signals and determination results of said determination in the frequency property determining step; and

program codes for a geometric transforming step of performing inverse transformation of said identified geometric transformation.

24. A computer data signal embodied in a propagating wave and used for implementing an image processing method of inputting image data with registration signals embedded therein, subjected to geometric transformation, and extracting registration signals from said inputted image data to perform registration processing, comprising:

code signals for use in a registration signal extracting step of extracting registration signals from said image data;

code signals for use in a frequency property determining step of determining frequency properties of said image data;

code signals for use in a geometric transformation identifying step of identifying geometric transformation to which said image data is subjected, using said extracted registration signals and determination results of said determination in the frequency property determining step; and

code signals for use in a geometric transforming step of performing inverse transformation of said identified geometric transformation.