Abstract: Methods, systems and apparatus for identifying modified images based on seed images that are known to be modified images. In an aspect, a method includes accessing data identifying a set of first seed images; for each first seed image, determining a respective first set of similar images from images in an image corpus, each similar image having a visual similarity score that is a measure of visual similarity of the similar image to the first seed image based on the image content of the similar image and the first seed image that satisfies a first seed image similarity threshold; and for each similar image in each respective first set of similar images, attributing to the similar image signal data of each first seed image for which the similar image has a respective visual similarity score satisfying the first seed image similarity threshold.

Abstract: Methods, systems and apparatus for identifying modified images based on visual dissimilarity to a first image. In an aspect, a method includes determining, for each of a first image and a second image, a respective set of local image feature descriptions; determining one or more unmatched regions of the images that include unmatched image features and that correspond to one or more same respective regions in both the first image and the second image; determining, for each of the one or more unmatched regions of the images, a modification measure based on the image data corresponding to the unmatched region in the first image and the image data corresponding to the unmatched region in the second image; and determining that the second image is a modification of the first image when one of the modification measures meets a modification measure threshold.

Abstract: A method for authenticating video content includes: receiving a digital signature, an unsecured video fingerprint, and an unsecured video content from a transmitting node at a receiving node in a communication network; determining if the digital signature is consistent with the unsecured video fingerprint at the receiving node to verify the unsecured video fingerprint; and determining if the unsecured video fingerprint is consistent with the unsecured video content at the receiving node to verify the unsecured video content in a manner that tolerates a predetermined measure of loss in the unsecured video content. If the unsecured video fingerprint and the unsecured video content are verified, the unsecured video content is authenticated for subsequent use at the receiving node. A receiving node associated with the method includes an input module, a fingerprint verification module, a content verification module, and a controller module.

Abstract: A method for comparing videos includes detecting local features in frames of a video and determining the positions of detected local features in a first frame compared to their respective positions in a succeeding second frame. For at least some of the detected local features, a movement indicator is generated representing the position of a local feature in the first frame relative to the position of that local feature in the second frame, the movement indicator including an orientation, to obtain a plurality of movement indicators. Movement indicators are grouped by orientation ranges. The number of grouped movement indicators in an orientation range are summed to obtain a value for that orientation range. A time series of values for at least one given orientation range is obtained by determining the positions of detected local features in a first frame compared to their respective positions in a succeeding second frame for a plurality of pairs of frames.

Abstract: A method for authenticating video content includes: receiving a digital signature, an unsecured video fingerprint, and an unsecured video content from a transmitting node at a receiving node in a communication network; determining if the digital signature is consistent with the unsecured video fingerprint at the receiving node to verify the unsecured video fingerprint; and determining if the unsecured video fingerprint is consistent with the unsecured video content at the receiving node to verify the unsecured video content in a manner that tolerates a predetermined measure of loss in the unsecured video content. If the unsecured video fingerprint and the unsecured video content are verified, the unsecured video content is authenticated for subsequent use at the receiving node. A receiving node associated with the method includes an input module, a fingerprint verification module, a content verification module, and a controller module.

Abstract: A method for comparing videos includes detecting local features in frames of a video and determining the positions of detected local features in a first frame compared to their respective positions in a succeeding second frame. For at least some of the detected local features, a movement indicator is generated representing the position of a local feature in the first frame relative to the position of that local feature in the second frame, the movement indicator including an orientation, to obtain a plurality of movement indicators. Movement indicators are grouped by orientation ranges. The number of grouped movement indicators in an orientation range are summed to obtain a value for that orientation range. A time series of values for at least one given orientation range is obtained by determining the positions of detected local features in a first frame compared to their respective positions in a succeeding second frame for a plurality of pairs of frames.