Signal Embedding and Detection using Circular Structures in a Transform Domain of a Media Signal

• US 20090285446A1
• Filed: 11/18/2008
• Published: 11/19/2009
• Est. Priority Date: 03/22/2001
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Stach, John, Sharma, Ravi K., Brunk, Hugh L.
• Granted Patent: US 7,986,807 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 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 21/00 Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility G10L19/00 takes precedence
• 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 1/32154 Transform domain methods H04N1/32309 takes precedence
• 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

Abstract

Machine readable signals embedded in other media signals include a circular structure in a transform domain to facilitate detection. The machine readable signals are not apparent to human observers of rendered media containing the machine readable signals, such as images and documents. A detector captures the media signal, transforms it to the transform domain, and then uses the circular structure in the transform domain to facilitate detection despite rotation of the media signal.

Claims

1. A physical document comprising an embedded pattern, the pattern incorporating a machine readable embedded signal not apparent to human observers of the document, the embedded signal forming a circular structure in frequency transform domain, the circular structure facilitating detection of the embedded signal in a digital image captured from the physical document despite rotation angle of the document;

the embedded signal also including a one dimensional signal used to facilitate detection.

2. The physical document of claim 1 wherein the frequency transform domain comprises a Fourier domain.

3. The physical document of claim 1 wherein the embedded signal comprises a pseudorandom phase.

4. The physical document of claim 1 wherein the one dimensional signal is arranged along a circle in the frequency transform domain.

5. The physical document of claim 1 wherein the embedded signal includes machine readable data that is hidden in an image by quantizing features of corresponding sets of image samples to correspond to the machine readable data.

6. A detector for detecting an embedded signal in a media signal, the detector comprising a memory, and a decoder for transforming the media signal into a transform domain and for detecting an embedded signal in a pattern comprising a circular structure in the transform domain, the circular structure facilitating detection of the embedded signal despite rotation angle of the media signal;

the embedded signal also including a one dimensional signal used to facilitate detection.