Image processing using embedded registration data to determine and compensate for geometric transformation

• US 20040264733A1
• Filed: 03/09/2004
• Published: 12/30/2004
• Est. Priority Date: 04/25/1996
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Sharma, Ravi K., Rhoads, Geoffrey B.
• Granted Patent: US 8,243,980 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: H04N 1/00005 relating to image data
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00079 remotely
• CPC Class Codes: H04N 1/32122 in a separate device, e.g. in a memory or on a display separate from image data
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• 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 1/3232 Robust embedding or watermarking
• 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 21/23892 involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• 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 2201/3205 of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 of an address
• CPC Class Codes: H04N 2201/3225 of data relating to an image, a page or a document
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• 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 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/3274 : Storage or retrieval of prestored additional information
• CPC Class Codes: H04N 2201/328 : Processing of the additional information

Abstract

Registration data embedded in an image is used to determine and compensate for geometric transformation of the image. The registration data may include frequency domain features of the image that are used to compute the rotation and/or scaling of the image. The registration method may be used in conjunction with digital watermarking and other signal processing applications.

Claims

1. 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.

2. 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.

3. 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.

4. The image processing method according to claim 1, wherein in said frequency transforming step, Fourier transformation is performed, and conversion into amplitude spectra of said frequency components is made.

5. 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.

6. The image processing method according to claim 1, wherein said geometric transformation is scaling.

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

means for detecting a feature of said image data;

means for selecting a registration signal from several possible registration signals in accordance with said detected feature; and

means for adding to said image data the registration signal so-selected.

8. 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.

9. 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 step of detecting a feature of said image data;

program codes for a step of selecting one registration signal from several possible registration signals in accordance with said detected feature; and

program codes for a step of adding to said image data the registration signal so-selected.

10. 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.

11. A computer data signal embodied in a two dimensional pattern 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.

12. An image processing method of embedding a registration signal in image data, comprising:

detecting a feature of said image data;

providing a registration signal in correspondence with said detected feature; and

adding said corresponding registration signal to the image data.

13. The image processing method according to claim 12, further comprising:

transforming said image data into frequency components; and

inverse transforming said frequency components into spatial components.

14. The image processing method according to claim 13 wherein Fourier transformation is performed to transform said image data into amplitude spectra.

15. A signal processing method for determining a geometric transformation applied to a media signal, the method comprising:

transforming the media signal into a frequency domain to produce frequency components of the media signal;

detecting an embedded signal in the frequency components;

based on the detecting, determining geometric transformation parameters defining a geometric transformation of the media signal; and

using the geometric transformation parameters to transform the media signal.

16. The method of claim 15 wherein the frequency components are computed using a Fourier transform.

17. The method of claim 15 including pre-filtering the media signal to attenuate noise relative to the embedded signal.

18. The method of claim 15 including performing a log sampling of the media signal.

19. The method of claim 18 including performing a log-log sampling of the media signal.

20. The method of claim 18 including performing a log-polar sampling of the media signal.