Method for encoding auxiliary data within a source signal

• US 6,385,330 B1
• Filed: 08/28/2001
• Issued: 05/07/2002
• Est. Priority Date: 07/31/1992
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Powell, Robert D., Nitzberg, Mark J.
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US09/941,365
• Publication Number:
  US 20020044673A1
• Time in Patent Office: 252 Days
• Field of Search: 382/100, 382/232, 380/210, 380/252, 380/287, 380/54, 713/176, 370/527, 370/529
• US Class Current: 382/100
• 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: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• 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 2201/0081 whereby both original and watermarked images are required at decoder, e.g. destination-based, non-blind, non-oblivious
• CPC Class Codes: G07D 7/0047 using checkcodes, e.g. coded numbers derived from serial number and denomination
• CPC Class Codes: G07D 7/0056 involving markings of altered colours
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: G07D 7/2008 using pre-processing, e.g. de-blurring, averaging, normalisation or rotation
• CPC Class Codes: G07D 7/2033 Matching unique patterns, i.e. patterns that are unique to each individual paper
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/12 Card verification
• CPC Class Codes: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take 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 1/32245 Random or pseudorandom selection of pixels
• CPC Class Codes: H04N 1/32251 in multilevel data, e.g. greyscale or continuous tone data
• 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 1/3232 Robust embedding or watermarking
• CPC Class Codes: H04N 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3235 : Checking or certification of the authentication information, e.g. by comparison with data stored independently
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes

Abstract

A method and system for embedding signatures within visual images in both digital representation and print or film. A signature is inseparably embedded within the visible image, the signature persisting through image transforms that include resizing as well as conversion to print or film among the pixels of an original image. The pixel values of the signature points and surrounding pixels are adjusted by an amount detectable by a digital scanner. The adjusted signature points form a digital signature which is stored for future identification of subject images derived from the image. In one embodiment, a signature is embedded within an image by locating relative extrema in the continuous space of pixel values and selecting the signature points from among the extrema. Preferably, the signature is redundantly embedded in the image such that any of the redundant representations can be used to identify the signature. Identification of a subject image includes ensuring that the subject image is normalized with respect to the original image or the signed image. Preferably, the normalized subject image is compared with the stored digital signature.

Claims

1. A method of processing an input image signal to extract steganographically hidden data, comprising:

discerning, from said input image signal, an N-bit code signal steganographically encoded therein, where N is greater than or equal to two, said discerning including performing an algorithmic registration process to resolve an initially unknown variable needed to discern the code signal from the input image signal, said input image signal corresponding to an originally encoded image corrupted by scaling and/or rotation processes, wherein the N-bit code signal is discerned notwithstanding said corruption.

2. The method of claim 1 in which said discerning includes:

analyzing said input image signal to determine at least one corruption characterization parameter, said parameter characterizing at least one aspect of said corruption; and

employing said corruption characterization parameter in discerning from said input image signal the N-bit code signal steganographically encoded therein.

3. The method of claim 2 which includes employing said corruption characterization parameter to compensate the input image signal for said corruption, and discerning the N-bit code signal from a compensated image signal.

4. The method of claim 2 in which said corruption characterization parameter is a scale factor.

5. The method of claim 2 in which said corruption characterization parameter is a rotation factor.

6. The method of claim 1 in which the input image signal is produced by a process in which the relative strength of the encoded N-bit code signal changes locally in accordance with local characteristics of the image signal.

7. The method of claim 1 in which said discerning is performed using a representation of said input image signal in the spatial image domain, rather than in a transformed domain.

8. A computer storage medium having stored thereon instructions for causing a programmable computer to perform the method of claim 1.