Abstract: The invention provides methods for embedding digital watermarks for authentication of printed objects, and corresponding methods for authenticating these objects. One aspect of the invention is a method of embedding a digital watermark in a digital image to be printed on an object. The method embeds an auxiliary signal in the digital image so that the auxiliary signal is substantially imperceptible, yet machine readable. It converts the image to a halftone image using a halftoning process. If copies are made of the printed image, the image characteristics change due a change in the halftoning process used to create the copies. These changes are detected to determine whether a suspect document is authentic.

Abstract: The present invention relates generally to fingerprinting, e.g., a reduced-bit representation or other identifier of a media signal (e.g., audio, video or still images). One method recites: receiving a partial fingerprint of a media signal, wherein the partial fingerprint is derived from the media signal itself, the partial fingerprint being computed a first location; processing the partial fingerprint to obtain a more refined fingerprint, relative to the partial fingerprint, the act of processing occurring at a second location that is remote from the first location; and based at least in part of the refined fingerprint, identifying the media signal or information associated with the media signal.

Abstract: Identification of media content, such as audio, can be performed through use of watermarking or fingerprinting (aka content signature) technologies. Aspects of these technologies may be combined to advantageous effect. For example, in dealing with the problem of fingerprint errors arising from object distortion, operations known from digital watermarking systems can be employed.

Abstract: The present invention generally relates to deriving and/or utilizing content signatures. A content signature includes a representation of a content item, which is derived from the content item itself. According to one embodiment of the invention, a method includes: obtaining a content item; transforming the content item to obtain transform domain coefficients; applying Viterbi decoding to at least a set of the transform domain coefficients; using at least one result of the Viterbi decoding as a content signature for the content item. Other embodiments are provided and claimed as well.

Abstract: The present invention relates to deriving and/or utilizing content signatures. A content signature includes a representation of a content item, which is derived from the content item itself. According to one embodiment of the invention, a method of generating a content signature for a signal is provided. The method includes: i) dividing the signal into at least one set; ii) transforming the set into a frequency-based domain; iii) determining features of the transformed set; and iv) grouping the features so as to form a content signature of the set. Other embodiments are provided and claimed too.

Abstract: A method of embedding a digital watermark into a halftone image. The method redundantly encodes a multi-bit message, and transforms the encoded message to a multilevel per pixel watermark image. It then derives halftone thresholds from the multilevel per pixel watermark image. These thresholds are then used to convert target images into watermarked halftone images. The multilevel pixels in the target image are used to select corresponding halftone thresholds from the halftone thresholds derived from the watermark image. The selected thresholds are applied to corresponding multilevel pixels in the watermark image to create the watermarked halftone image of the target image. A method of measuring digital watermark strength. In this method, a watermarked signal is processed to extract estimates of error correction encoded bits embedded into the watermarked signal. Then, the error correction encoded bits are decoded to compute a message payload.

Abstract: The present invention relates to digital watermarks integrated into holograms, watermarked hologram structures, and related applications as an authentication technique. One method creates a watermark image, and then embeds the watermark image into a holographic structure. The holographic structure is carried by a smart card. The smart card includes additional information. In one embodiment, the digital watermark includes information bits, and these information bits are used to authenticate the hologram, or the smart card. In another embodiment, the watermark's information bits are compared with the additional information carried by the smart card. The result of the comparison is used to authenticate the smart card or the hologram.

Abstract: The present invention relates to message encoding. In a first implementation, a message is provided. The message is transformed by a secret key. The secret key is generated by providing a plural-bit seed. The seed is randomized and then error correction encoded. We prefer tail-biting convolutional encoding for our error correction encoding. The encoded seed forms a secure key, which is used to transform the message prior to embedding.

Abstract: The present invention relates generally to fingerprinting (i.e., human fingerprints). More specifically the present invention relates to explicitly embedding so-called fingerprint minutiae locations in an identification document via digital watermarking. A relative mapping of the minutiae locations can be transformed, scrambled and combined with a watermark orientation component, and then embedded in a photograph or artwork. The embedded photograph or artwork is printed on, e.g., an identification document. Another aspect of the invention is a matching method used to match a representation of a set of control minutiae locations with a representation of a set of sample minutiae locations.

Abstract: The present invention provides a mechanism for automatically setting the exposure time and gain of an electronic camera so that the acquired image has improved characteristics for the detection of a digital watermark. With the present invention the exposure time and gain of an electronic camera are set by first directing the camera at a test target with the camera's controls set to a default set of values. The system then calculates a histogram of the luminance values of the pixels in the image. Next characteristic values from the histogram such as the peak value, the centroid value, the RMS value, the median value, etc. are calculated. One or more of the characteristic values of the histogram are then applied as an index or pointer to values of pre-established settings that are stored in a table. Values from the table are used to set the exposure time and/or gain of the camera. In some embodiments, the variance of the luminance histogram is also measured and used to index data from the table.

Abstract: The present invention provides a mechanism for automatically setting the exposure time and gain of an electronic camera so that the acquired image has improved characteristics for the detection of a digital watermark. With the present invention the exposure time and gain of an electronic camera are set by first directing the camera at a test target with the camera's controls set to a default set of values. The system then calculates a histogram of the luminance values of the pixels in the image. Next characteristic values from the histogram such as the peak value, the centroid value, the RMS value, the median value, etc. are calculated. One or more of the characteristic values of the histogram are then applied as an index or pointer to values of pre-established settings that are stored in a table. Values from the table are used to set the exposure time and/or gain of the camera. In some embodiments, the variance of the luminance histogram is also measured and used to index data from the table.

Abstract: The present invention provides a mechanism for automatically setting the exposure time and gain of an electronic camera so that the acquired image has improved characteristics for the detection of a digital watermark. With the present invention the exposure time and gain of an electronic camera are set by first directing the camera at a test target with the camera's controls set to a default set of values. The system then calculates a histogram of the luminance values of the pixels in the image. Next characteristic values from the histogram such as the peak value, the centroid value, the RMS value, the median value, etc. are calculated. One or more of the characteristic values of the histogram are then applied as an index or pointer to values of pre-established settings that are stored in a table. Values from the table are used to set the exposure time and/or gain of the camera. In some embodiments, the variance of the luminance histogram is also measured and used to index data from the table.