Koninklijke Philips Corporation N.v.

Civolution B.v.

Teletrax B.v.

Gerrit Cornelis Langelaar

Johan Cornelis Talstra

Job Cornelis Oostveen

Antonius Adrianus Cornelis Maria Kalker

Jaap Andre Haitsma

Frits A Steenhof

Mehmet Utku Celik

Maurice Jerome Justin Jean-Baptiste Maes

Martijn Maas

Jungong Han

Method and system for generating a fingerprint representing a portion of an information signal. The method comprises decomposing a portion of the information signal into plural frequency sub bands at a decomposition level, calculating a spectral property of the signal in each of said plural frequency sub bands, comparing each spectral property against a first criterion thereby generating a comparison result, combining each comparison result for constituting the fingerprint, at least once repeating the decomposing, calculating, comparing and combining, wherein for each repetition the decomposing is performed using a decomposition level different from a previous decomposition level.

Method and device for generating fingerprints of information signals

Client terminals report an easy-to-calculate identifier such as the Internet URL or a cryptographic hash of the content to a server. The server collects and counts the reported identifiers so as to obtain preliminary statistics. By aggregating these reported identifiers into the preliminary statistics, identifiers are revealed that are likely popular content. The server selects one or more identifiers from the preliminary statistics and makes these available to at least a subset of clients. The clients that obtain these one or more identifiers then access content and compute the easy-to-calculate identifiers as usual. If the computed identifier matches one of the identifiers obtained from the server, the client will additionally extract a watermarked identifier or compute a digital fingerprint of the content in question and report this to the server. The server then uses the received identifier or fingerprint to create final statistics by aggregating the preliminary statistics.

Generating statistics of popular content

Advanced watermark embedders use psycho visual/acoustic models to minimize perception of the embedded watermark in media contents. However, it is expensive to implement such advanced watermark embedders in consumer appliances () such as DVD recorders. In accordance with the invention, embedding strength parameters (JND) are calculated () off-line at a remote location () and transmitted along with the media contents to the consumer appliance (). A relatively simple embedder () uses the received parameters to control the strength of the watermark () to be embedded. The parameters may be accommodated in the transmitted signal as payload of a fragile watermark or as user data in an encrypted MPEG stream.

Watermark embedding

Watermark detectors have a buffer in which a number of image tiles are folded and accumulated prior to computing the correlation between buffer contents and the watermark pattern being looked for. The intention of the folding and accumulation process is to average out the video content while accumulating the embedded watermark energy. This no longer appears to hold for strongly compressed video, such as DIVX, which exhibits a lot of artificial noise and undesired similarity (block patterns). As a result thereof, correlation peaks are often below the threshold. In a similar manner, the compression affects scale detection. According to this invention, only frames (or parts thereof) that are not so heavily compressed and therefore have a high probability of carrying enough watermark energy are folded and accumulated. To this end, a quality metric is calculated, the quality metric being indicative of the degree of compression of the data. The quality metric may be calculated based on the compressed data itself or derived from the decompressed base-band data. An advantageous example is the number of non-zero DCT coefficients of a (residue) frame. A determination is then made as to whether to exclude the frame (or part thereof) from the watermark decode process. The quality metric may also be used to select data for use in a scale detection process.

Detection of a watermark in a digital signal

A graphics card of a computer system is configured to detect watermarks within a video signal that includes one or more windows of a display. The frames of the video signal are analyzed to locate image areas in which the video signal changes, and a bounding box around these areas of change is defined as an area(s) of interest. Watermark detection is then performed within the area(s) of interest.

Method and arrangement for watermark detection

A method and apparatus () for embedding a watermark in an information signal bit-stream are described. The method comprises receiving a portion of an information signal bit-stream (MPEG2). A first copy of the received portion is stored in a first buffer (). A second copy of the received portion is watermarked, and the resulting watermarked signal stored in a second buffer (). At predetermined intervals, a check is performed to determine if the bit-rate of the received portion has been changed by being watermarked. If the check determines the bit-rate has changed, the first copy of the received portion from the first buffer is output. Otherwise the watermarked signal from the second buffer is output.

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Eindhoven, Netherlands

Gerrit Cornelis Langelaar