Optimized digital watermarking functions for streaming data

• US 7,480,393 B2
• Filed: 12/10/2004
• Issued: 01/20/2009
• Est. Priority Date: 11/19/2003
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Gustafson, Ammon E., Lyons, Robert G.
• Primary Examiner(s): Tabatabai; Abolfazl
• Application Number:
  US11/009,694
• Publication Number:
  US 20050169497A1
• Time in Patent Office: 1,502 Days
• Field of Search: 382/100, 382/232, 382/240, 382/276, 382/279, 382/280, 382/281, 382/302, 382/303, 380/51, 380/54, 380/201, 380/210, 380/252, 380/287, 713/176, 713/179, 370522-529, 283/72, 283 74- 81, 283/85, 283/93, 283/901, 283/902
• US Class Current: 382/100
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• 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: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection

Abstract

In one aspect of the invention, a digital watermark detector comprises a memory buffer for managing an incoming stream of data. The detector includes logic for transferring overlapping data blocks from the memory buffer to a frequency domain transform processor, such as an FFT processor. The frequency domain transform processor including logic to re-use frequency domain transform operation results for overlapping portions of the data blocks. In another aspect of the invention, a digital watermark detector comprises a memory buffer for a block of data, and pipelined watermark processor segments. The segments each perform different watermark detector operations in series. These segments concurrently operate on different data segments of the block of data in a processing pipeline. One embodiment employs pipelined processors for setting up data for subsequent detecting stages, such as pipelined data conversion, re-sampling, pre-filtering and frequency domain transforms. Alternative embodiments pipeline data transformations, correlation operations (e.g., matched filter operations) etc. Data flows through the processing pipeline until it reaches a critical point. At stages before the critical point, data may be dropped as not likely to include digital watermark data. This pruning of data helps reduce un-needed processing and/or false positives of watermark detection.

Claims

1. A digital watermark detector comprising:

a memory buffer for managing an incoming stream of data;

logic for transferring overlapping data blocks from the memory buffer to a frequency domain transform processor, the frequency domain transform processor including logic to re-use frequency domain transform operation results for overlapping portions of the data blocks.

2. The digital watermark detector of claims 1 wherein the frequency domain transform processor comprises an FFT processor.

3. The digital watermark detector of claim 1 wherein the memory buffer buffers bands of image data, and overlapping blocks comprise overlapping blocks along horizontal rows of the bands.

4. The digital watermark detector of claim 1 including pipelined detector stages operable to perform pipelined processing of segments of data from the incoming stream of data.

5. The digital watermark detector of claim 1 wherein the stream comprises rows of image pixels and the frequency domain processor is longer in the direction of the rows to exploit greater resolution of image data along the rows.

6. A digital watermark detector comprising:

a memory buffer for a block of data; and

pipelined watermark processor segments, the segments each performing different watermark detector operations in series;

the segments concurrently operating on different data segments of the block of data in a processing pipeline.

7. The digital watermark detector of claim 6 wherein the pipelined watermark processor segments perform a frequency domain transform on the block of data.

8. The digital watermark detector of claim 7 wherein the frequency domain transform comprises filtering and frequency domain transform stages.

9. The digital watermark detector of claim 6 wherein the pipelined watermark processor elements perform a 1-dimensional frequency domain transform across a row of pixel data, and the detector accumulates results of the 1-dimensional transform for multiple rows before performing another frequency domain transform for columns of data in the multiple rows.