Removal of fixed pattern noise and other fixed patterns from media signals

• US 6,535,617 B1
• Filed: 04/19/2000
• Issued: 03/18/2003
• Est. Priority Date: 02/14/2000
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B., Hannigan, Brett T., Bradley, Brett A.
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US09/553,001
• Time in Patent Office: 1,063 Days
• Field of Search: 382/100, 382/232, 382/263, 382/275, 382/284, 382/286, 713/176, 380/210, 380/252, 380/287, 380/54, 348/607, 348/615, 381/94.1, 704/226, 704/227, 704/228, 327/551
• US Class Current: 382/100
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 19/06046 Constructional details
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: G06K 2019/06253 for a specific application
• CPC Class Codes: G06K 7/1417 2D bar codes
• CPC Class Codes: G06K 7/1447 extracting optical codes from image or text carrying said optical code
• CPC Class Codes: G06Q 20/1235 with control of digital rights management [DRM]
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/40145 Biometric identity checks
• 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 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0064 for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06V 10/30 Noise filtering
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: G07D 7/0034 using watermarks
• CPC Class Codes: G07D 7/004 using digital security elements, e.g. information coded on a magnetic thread or strip
• CPC Class Codes: G07F 7/086 : by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/1008 : Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G10L 19/018 : Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G11B 20/00891 : embedded in audio data
• CPC Class Codes: H04H 20/31 : using in-band signals, e.g. subsonic or cue 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 1/32203 : Spatial or amplitude domain methods H04N1/32309 takes 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 1/32288 : Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
• 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 19/467 : characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 19/645 : by grouping of coefficients into blocks after the transform
• 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 21/44008 : involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 21/4627 : Rights management associated to the content security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• 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 2201/323 : for tracing or tracking, e.g. forensic tracing of unauthorized copies
• 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 2201/3284 : for error correction
• CPC Class Codes: H04N 7/163 : by receiver means only

Abstract

A method of removing fixed pattern noise derives an estimate of fixed pattern noise from a composite media signal and uses the estimate to evaluate and remove fixed pattern noise from selected frames. The technique is particularly suited for removing fixed pattern noise in images due to image capture processes, but applies to other media signals as well. In watermarking applications, the method can be used to improve detection and recovery of a watermark. Also, it may be used to remove components of a watermark or a watermark from a cover signal that contains two or more different watermarks.

Claims

1. A method of removing noise from a media signal comprising:

combining frames of the media signal to form a composite signal;

removing a DC component from the composite signal;

deriving a measure of fixed pattern noise from the composite signal;

using the measure of fixed pattern noise to compute an estimate of fixed pattern noise in a frame of the media signal; and

removing the estimate of fixed pattern noise from the frame.

2. The method of claim 1 wherein the media signal is a collection of frames captured with an image sensor.

3. The method of claim 1 wherein the media signal comprises a collection of audio frames.

4. The method of claim 1 wherein the media signal comprises a video sequence.

5. The method of claim 1 wherein deriving the measure of fixed pattern noise includes normalizing the composite signal.

6. The method of claim 5 wherein normalizing the composite signal includes removing average energy from the composite signal.

7. The method of claim 1 used as a preprocessing stage for decoding a watermark from the media signal.

8. The method of claim 1 wherein the frames of the media signal are transformed to a transform domain before being processed for removal of the fixed pattern noise.

9. The method of claim 8 wherein the transform domain is a frequency domain.

10. The method of claim 9 wherein the frames are transformed using a fast Fourier transform.

11. The method of claim 1 including using the estimate of fixed pattern noise to remove a first watermark or component of a watermark.

12. The method of claim 11 including:

after removing the component of the first watermark or the component of a watermark, decoding a second watermark or another watermark component from the media signal.

13. A computer readable medium having software for performing the method of claim 1.

14. A watermark decoder preprocessor comprising:

a compositer for combining frames of a media signal into a composite signal;

a filter for removing a DC component from the composite signal and creating a measure of fixed pattern noise;

an estimater for using the measure of fixed pattern noise to estimate fixed pattern noise in a selected frame of the media signal; and

a remover for removing the estimate of the fixed pattern noise from the selected frame.

15. The preprocessor of claim 14 wherein the media signal is a collection of image frames.

16. The preprocessor of claim 14 wherein the media signal is a collection of audio frames.

17. A watermark decoder preprocessor comprising:

means for combining frames of a media signal into a composite signal;

means for computing a measure of fixed pattern noise;

means for using the measure of fixed pattern noise to estimate fixed pattern noise in a selected frame of the media signal; and

means for removing the estimate of the fixed pattern noise from the selected frame.

18. The preprocessor of claim 17 wherein the media signal is a collection of image frames.

19. The preprocessor of claim 17 wherein the media signal is a collection of audio frames.

20. A method of removing fixed pattern noise from an image signal comprising:

combining frames of images captured from an image sensor into a composite image;

applying a high pass filter to the composite image;

normalizing the composite signal by removing an average energy from the composite signal;

deriving a measure of fixed pattern noise from the normalized composite signal;

using the measure of fixed pattern noise to compute an estimate of fixed pattern noise in a selected image captured from the image sensor; and

subtracting the estimate of fixed pattern noise from the selected image.