On Tuesdays the USPTO issues new patents. Today's Spotlight Patents deal with aspects of digital fingerprinting and digital watermarking. Assigned to Landmark Digital Services, the first patent concerns techniques for recognizing sound and music signals in high noise and distortion. Assigned to NTT, the second patent concerns watermarking techniques that ential Fourier transforms.
7,865,368,"System and methods for recognizing sound and music signals in high noise and distortion," assigned to Landmark Digital Services, LLC.
A method for recognizing an audio sample locates an audio file that most closely matches the audio sample from a database indexing a large set of original recordings. Each indexed audio file is represented in the database index by a set of landmark timepoints and associated fingerprints. Landmarks occur at reproducible locations within the file, while fingerprints represent features of the signal at or near the landmark timepoints. To perform recognition, landmarks and fingerprints are computed for the unknown sample and used to retrieve matching fingerprints from the database. For each file containing matching fingerprints, the landmarks are compared with landmarks of the sample at which the same fingerprints were computed. If a large number of corresponding landmarks are linearly related, i.e., if equivalent fingerprints of the sample and retrieved file have the same time evolution, then the file is identified with the sample. The method can be used for any type of sound or music, and is particularly effective for audio signals subject to linear and nonlinear distortion such as background noise, compression artifacts, or transmission dropouts. The sample can be identified in a time proportional to the logarithm of the number of entries in the database; given sufficient computational power, recognition can be performed in nearly real time as the sound is being sampled.
7,860,270, "Digital watermark embedding method, digital watermark embedding apparatus, and storage medium storing a digital watermark embedding program," assigned to Nippon Telegraph and Telephone Corporation (JP).
A method for embedding a watermark into digital data by independently changing real and imaginary number components of the coefficient values of a complex watermark coefficient matrix using a key, performing a discrete Fourier inverse transform on the sequence matrix of the changed watermark and generating a watermark pattern, adding like tiling the water mark pattern to the original image, and generating an embedded image. A watermark detection method includes separating a block from an arbitrary position on the detected object image, performing a discrete Fourier transform on the block and obtaining a sequence matrix, generating position information for a component which is to be detected and is specified by the key, detecting a position marker sequence by calculating a phase difference of a sequence by a parallel displacement, for the position information, extracting offset information, and detecting the embedded watermark from the detected object image.