Computing distortion of media signals embedded data with repetitive structure and log-polar mapping

• US 7,152,021 B2
• Filed: 08/06/2003
• Issued: 12/19/2006
• Est. Priority Date: 08/15/2002
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Alattar, Adnan M., Meyer, Joel R.
• Primary Examiner(s): Tsai, Carol S. W.
• Application Number:
  US10/636,515
• Publication Number:
  US 20040133427A1
• Time in Patent Office: 1,231 Days
• Field of Search: 702 57- 59, 702/62, 702 66- 71, 702/79, 702/80, 702/84, 702/106, 702/FOR.103, 702/FOR.104, 702/FOR.110, 702/FOR.166, 370493-495, 370/503, 370/468, 370508-510, 370/512, 370/516, 342/26, 342/28, 342/104, 342/107, 342/109, 342113-115, 342/118, 342/134, 342/139, 342/146, 342/147, 342/175, 342/195, 342/101, 342/159, 342202-204, 455/295, 455/296, 455/63.1, 455302-306, 375/220
• US Class Current: 702/191
• 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: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection

Abstract

A digital watermark detection method uses a matched filtering technique on a log polar re-mapping of a watermarked signal to detect peaks associated with a repetitive structure of a watermark.

Claims

1. A method of determining distortion of a signal with embedded data comprising:

transforming the signal into a transform domain to produce peaks due to a repetitive structure of the embedded data in the signal;

performing a mapping of the transformed signal to convert distortion of the embedded data into a shift; and

performing a correlation of the mapped signal with a signal representing an expected pattern of peaks associated with the repetitive structure of the embedded data signal, wherein the correlation detects the shift, and the shift provides a measure of the distortion of the signal.

2. The method of claim 1 wherein transforming comprises an autocorrelation of the signal.

3. The method of claim 1 wherein the mapping includes a log-polar mapping to convert scaling and rotation into spatial shifts.

4. The method of claim 1 wherein the correlation is computed using a matched filter.

5. The method of claim 1 wherein the embedded data is repeated in the signal as rectangular blocks.

6. A tangible medium on which is stored instructions for performing the method of claim 1.