Digital watermarking of low bit rate video

• US 7,567,721 B2
• Filed: 08/06/2003
• Issued: 07/28/2009
• Est. Priority Date: 01/22/2002
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Celik, Mehmet, Lin, Eugene T., Alattar, Adnan M.
• Primary Examiner(s): Tucker; Wesley
• Application Number:
  US10/636,505
• Publication Number:
  US 20040125952A1
• Time in Patent Office: 2,183 Days
• Field of Search: 382/100, 382/202, 382/239, 382/269, 382/248, 382/276, 382/278
• US Class Current: 382/248
• 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 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• 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
• CPC Class Codes: G06T 2201/0601 whereby calibration information is embedded in the watermark, e.g. a grid, a scale, a list of transformations

Abstract

Methods for embedding digital watermarks in compressed video include perceptual adapting a digital watermark in predicted and non-predicted data based on block activity derived from the compressed video stream, embedding in predicted objects in a video stream having separately compressed video objects, and bit rate control of watermarked video.

Claims

1. A method for embedding a digital watermark in a compressed video stream comprising:

receiving a compressed video stream;

extracting transform domain coefficients from the compressed video stream;

computing an adaptive watermark signal strength based on an activity estimate of the transform domain coefficients; and

embedding the adapted watermark signal into the transform domain coefficients;

wherein computing the activity estimate includes computing activity for a block of transform coefficients and weighting the watermark signal strength for the block based on the activity for the block relative to the activity of other blocks in the video stream.

2. The method of claim 1 wherein the video stream includes one or more separately compressed video objects, and the watermark strength for a block in a video object is weighted based on the activity of the block relative to the activity of other blocks in the same video object.

5. A computer readable medium on which is stored instructions, which, when executed by computer, perform the method of claim 1.

3. A method for embedding a digital watermark in a compressed video stream comprising:

receiving a compressed video stream;

extracting transform domain coefficients from the compressed video stream;

computing an adaptive watermark signal strength based on an activity estimate of the transform domain coefficients; and

embedding the adapted watermark signal into the transform domain coefficients, wherein the adaptive watermark signal is computed for non predicted and predicted video data; and

wherein the watermark signal strength derived from non-predicted video data is used along with motion information that describes motion between the predicted and non-predicted video data to compute watermark signal strength for predicted video data.

4. The method of claim 3 wherein the motion information is extracted from motion vectors in the compressed video stream.

7. The method of claim 3 including:

extracting prediction information from the compressed video stream, the prediction information including motion vectors; and

computing the adaptive watermark signal strength based on the prediction information.

8. The method of claim 7 wherein the prediction information includes spatial prediction information from the compressed video stream.

9. The method of claim 7 wherein the prediction information includes temporal prediction information from the compressed video stream.

10. The method of claim 7 wherein the prediction information includes temporal and spatial prediction information from the compressed video stream.

12. A computer readable medium on which is stored instructions, which, when executed by computer, perform the method of claim 3.

6. A method for embedding a digital watermark in a compressed video stream comprising:

receiving a compressed video stream;

extracting transform domain coefficients from the compressed video stream;

computing an adaptive watermark signal strength based on an activity estimate of the transform domain coefficients; and

embedding the adapted watermark signal into the transform domain coefficients;

wherein the activity estimate is derived from energy of transform coefficients extracted from the compressed video stream;

including;

for blocks of transform coefficients embedded with the watermark signal, controlling bit rate of the data stream by selectively eliminating non-zero quantized transform coefficients with smallest magnitude in the block according to a bit allocation method that assigns a bit budget per block.

11. A computer readable medium on which is stored instructions, which, when executed by computer, perform the method of claim 6.