Digital data watermarking system using novel watermark insertion and detection methods
AssigneeThomson Licensing
InventorsTeddy Furon, Pierre Duhamel
Life of this patent
Estimating the term…
Abstract
The watermarking system uses a first series of parameters, the private key, for the insertion of the watermark, and a second series of parameters, the public key, for the detection of the watermark, so that knowledge of the public key does not make it possible to know the private key and does not make it possible to delete or modify the watermark. The insertion of the watermark is performed by adding a pseudo random noise sequence, filtered by a filter with impulse response, to the data to be watermarked. The detection of the watermark is performed by searching through the data received for whether they contain noise which has been filtered by a filter with predefined spectral response. Application to copy protection.
Claims10
A method for inserting a watermark into data (x) representing a content to be protected, comprising the steps of:
- a) generating, from said data (x), a modulation sequence (m) representing the maximum amount of noise which can be added to said data,
- b) supplying a pseudo random noise sequence (v) to the input of a filter with predefined impulse response (h);
- c) multiplying said filtered pseudo noise sequence (w) with said modulation sequence;
- and
- d) adding the filtered pseudo noise sequence (w) multiplied by the modulation sequence to said data.
A method for detecting a watermark in data (r) representing a content received, comprising the steps of:
- i) performing a spectral analysis of said data;
- ii) estimating therefrom whether said data include a pseudo noise sequence which has been filtered by a filter with predefined spectral response (H(f));
- and
- iii) deducing from said estimation the presence of said watermark.
A device for inserting a watermark into data (x) representing a content to be protected, comprising:
- means for generating a pseudo random noise sequence (v);
- means for generating, from said data (x), a modulation sequence (m) indicative of the maximum amount of noise which can be added to said data;
- filtering means having a predefined impulse response (h) and which are adapted for receiving said pseudo noise sequence (v) and for supplying a filtered pseudo noise sequence (w);
- multiplication means for multiplying said filtered pseudo noise sequence (w) with said modulation sequence;
- and
- means for adding the filtered pseudo noise sequence (w) multiplied by the modulation sequence (m) to said data (x).
A device for detecting a watermark in data (r) representing a content received, comprising:
- means for obtaining the power spectral density of said data;
- means of likelihood testing of hypotheses so as to estimate whether said data include a pseudo noise sequence which has been filtered by a filter with predefined spectral response (H(f));
- and
- means for deducing from said estimation the presence of said watermark.
Dependencies are inferred from the claim text.