Adaptive prediction filtering for encoding/decoding digital signals in media content

• US 8,315,427 B2
• Filed: 03/30/2010
• Issued: 11/20/2012
• Est. Priority Date: 01/22/2002
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Bradley, Brett A.
• Primary Examiner(s): Bali, Vikkram
• Application Number:
  US12/750,579
• Publication Number:
  US 20100303283A1
• Time in Patent Office: 966 Days
• Field of Search: 382/100
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial 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: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32331 Fragile embedding or watermarking

Abstract

A method computes signal characteristics of a host signal in which a digital signal is encoded, and analyzes the characteristics to determine an extent to which the signal characteristics correspond to characteristics of the digital signal. The method adapts parameters of a predictive filter or prediction function applied to the host signal based on the extent to which the signal characteristics correspond to the characteristics of the digital signal. In one embodiment, different filters or filter parameters are selected to match different signal characteristics of the host signal with the characteristics of the digital signal. These predictive filtering techniques also enable optimized encoding of digital signals that adapt the encoding of digital signals to take advantage of predictive filtering in the decoding process.

Claims

1. A method comprising:

computing, using a computing device, signal characteristics of a host signal in which a digital signal is encoded;

analyzing, using the computing device, the signal characteristics of the host signal to determine an extent to which the signal characteristics of the host signal correspond to signal characteristics of the digital signal; and

adapting, using the computing device, parameters of a predictive filter applied to the host signal based on the extent to which the signal characteristics of the host signal correspond to the signal characteristics of the digital signal, wherein the parameters correspond to a type of prediction filter that is selected based on the signal characteristics of the host signal.

2. The method of claim 1, wherein the predictive filter predicts an estimate of a digital signal element based on comparison of a host signal value and one or more other related values.

3. The method of claim 1, wherein the analyzing comprises determining correlation between the host signal characteristics and the signal characteristics of the digital signal.

4. The method of claim 3, wherein the adapting includes adapting the parameters to increase correlation between outputs of the prediction and the signal characteristics of the digital signal.

5. The method of claim 1, wherein analyzing includes analyzing the signal characteristics of different portions of the host signal, wherein adapting parameters comprises selecting different prediction filters for the different portions of the host signal, and wherein the prediction filters are selected to provide better correspondence between output of the selected filters and the characteristics of the digital signal.

6. A tangible computer-readable medium on which is stored instructions, which when executed by a computing device, cause the computing device to perform operations comprising:

computing signal characteristics of a host signal in which a digital signal is encoded;

analyzing the signal characteristics of the host signal to determine an extent to which the signal characteristics of the host signal correspond to signal characteristics of the digital signal; and

adapting parameters of a predictive filter applied to the host signal based on the extent to which the signal characteristics of the host signal correspond to the signal characteristics of the digital signal, wherein the parameters correspond to a type of prediction filter that is selected based on the signal characteristics of the host signal.

7. The tangible computer-readable medium of claim 6, wherein the predictive filter predicts an estimate of a digital signal element based on comparison of a host signal value and one or more other related values.

8. The tangible computer-readable medium of claim 6, wherein the analyzing comprises determining correlation between the host signal characteristics and the signal characteristics of the digital signal.

9. The tangible computer-readable medium of claim 6, wherein analyzing includes analyzing the signal characteristics of different portions of the host signal, wherein adapting parameters comprises selecting different prediction filters for the different portions of the host signal, and wherein the prediction filters are selected to provide better correspondence between output of the selected filters and the characteristics of the digital signal.

11. The tangible computer-readable medium of claim 8, wherein the adapting includes adapting the parameters to increase correlation between outputs of the prediction and the signal characteristics of the digital signal.

10. A method comprising:

assessing, using a computing device, characteristics of a host signal, and determining an initial filter function based on the characteristics of the host signal;

filtering, using the computing device, a digital signal in accordance with the initial filter function;

assessing, using the computing device, the host signal relative to the digital signal to determine a second filter function, wherein the second filter function is adapted based on an assessment of host signal characteristics relative to digital signal characteristics; and

filtering the host signal in accordance with the second filter function.

12. A method comprising:

processing, using a computing device, a host signal to obtain an initial estimate of a plural symbol message and reliability of the initial estimate;

based on the initial estimate and the reliability of the initial estimate, adapting parameters of a predictive filter, using the computing device, wherein a filter function is adapted based on the initial estimate;

processing the host signal using the predictive filter; and

decoding a digital signal from the processed signal.