Telecom Italia S.p.a.

Telecom Italia Lab S.p.a.

Massimo Balestri

Gianluca Francini

Skjalg Lepsoy

Gianluca De Petris

Barbara Silano

Skjalg LEPSØY

A method () for comparing a first video shot (Vs) comprising a first set of first images (I(s)) with a second video shot (Vs) comprising a second set of second images (I(t)), at least one between the first and the second set comprising at least two images. The method comprises pairing () each first image of the first set with each second image of the second set to form a plurality of images pairs (IP(m)), and, for each image pair, carrying out the operations a)-g): a) identifying () first interest points in the first image and second interest points in the second image; b) associating () first interest points with corresponding second interest points in order to form corresponding interest point matches; c) for each pair of first interest points, calculating () the distance therebetween for obtaining a corresponding first length; d) for each pair of second interest points, calculating () the distance therebetween for obtaining a corresponding second length; e) calculating a plurality of distance ratios (), each distance ratio corresponding to a selected pair of interest point matches and being based on a ratio of a first term and a second term or on a ratio of the second term and the first term, said first term corresponding to the distance between the first interest points of said pair of interest point matches and said second term corresponding to the distance between the second interest points of said pair of interest point matches; f) computing () a first representation of the statistical distribution of the plurality of calculated distance ratios; g) computing () a second representation of the statistical distribution of distance ratios obtained under the hypothesis that all the interest point matches in the image pair are outliers. The method further comprises generating () a first global representation of the statistical distribution of the plurality of calculated distance ratios computed for all the image pairs based on the first representations of all the image pairs; generating () a second global representation of the statistical distribution of distance ratios obtained under the hypothesis that all the interest point matches in all the image pairs are outliers based on the second representations of all the image pairs; comparing () said first global representation with said second global representation, and assessing () whether the first video shot contains a view of an object depicted in the second video shot based on said comparison.

Method and system for comparing video shots

A method for identifying keypoints in a digital image including a set of pixels. Each pixel has associated thereto a respective value of an image representative parameter. The method includes approximating a filtered image. The filtered image depends on a filtering parameter and includes for each pixel of the image a filtering function that depends on the filtering parameter to calculate a filtered value of the value of the representative parameter of the pixel. The approximating includes: a) generating a set of base filtered images; each base filtered image is the image filtered with a respective value of the filtering parameter; b) for each pixel of at least a subset of the set of pixels, approximating the filtering function by a respective approximation function based on the base filtered images; the approximation function is a function of the filtering parameter within a predefined range of the filtering parameter.

Keypoint identification

A method for processing an image, including: identifying a group of keypoints in the image; for each keypoint, calculating a corresponding descriptor array including plural array elements, each array element storing values taken by a corresponding color gradient histogram of a respective sub-region of the image in the neighborhood of the keypoint; for each keypoint, subdividing the descriptor array in at least two sub-arrays each including a respective number of elements of the descriptor array, and generating a compressed descriptor array including a corresponding compressed sub-array for each of the at least two sub-arrays, each compressed sub-array obtained by compressing the corresponding sub-array by vector quantization using a respective codebook; exploiting the compressed descriptor arrays of the keypoints for image analysis. For each keypoint of the group, the subdividing is based on correlation relationships among color gradient histograms with values stored in the elements of the descriptor array of each keypoint.

Method and system for image analysis based upon correlation relationships of sub-arrays of a descriptor array

A method for processing an image is proposed. The method comprises identifying a first group of keypoints in the image. For each keypoint of the first group, the method provides for identifying at least one corresponding keypoint local feature related to said each keypoint; for said at least one keypoint local feature, calculating a corresponding local feature relevance probability; calculating a keypoint relevance probability based on the local feature relevance probabilities of said at least one local feature. The method further comprises selecting keypoints, among the keypoints of the first group, having the highest keypoint relevance probabilities to form a second group of keypoints, and exploiting the keypoints of the second group for analyzing the image. The local feature relevance probability calculated for a local feature of a keypoint is obtained by comparing the value assumed by said local feature with a corresponding reference statistical distribution of values of said local feature.

Image analysis

A method for processing an image includes: identifying a group of keypoints in the image; for each keypoint of the group; a) calculating a corresponding descriptor array including a plurality of array elements, each array element storing values taken by a corresponding color gradient histogram of a respective sub-region of the image in the neighborhood of the keypoint; b) generating at least one compressed descriptor array by compressing at least one portion of the descriptor array by vector quantization using a codebook including a plurality of codewords.

Method and system for image analysis

A method for processing an image including: identifying a first group of keypoints in the image; for each keypoint of the first group, identifying at least one corresponding keypoint local feature related to the each keypoint; for the at least one keypoint local feature, calculating a corresponding local feature relevance probability; calculating a keypoint relevance probability based on the local feature relevance probabilities of the at least one local feature; selecting keypoints, among the keypoints of the first group, having the highest keypoint relevance probabilities to form a second group of keypoints, and exploiting the keypoints of the second group for analyzing the image. The local feature relevance probability calculated for a local feature of a keypoint is obtained by comparing the value assumed by the local feature with a corresponding reference statistical distribution of values of the local feature.

A server communicates a set of entitlement data representative of the entitlement of a client to access corresponding contents data by using a set of keys and a non-invertible cryptographic function. The cryptographic function is applied to a set of candidate bit strings using the set of keys to find a selected bit string that produces the set of entitlement data as a result of the application of the non-invertible cryptographic function by using the keys in the set. The server and the client share the cryptographic function as well as the set of keys (or the selected bit string). The server transmits to the client the selected bit string (or the set of keys). In either case, the client is thus in a position to apply the cryptographic function to the selected string of bits by using the set of keys, thereby reconstructing the set of entitlement data.

Method for communicating entitlement data from a server, related server, client systems and computer program product

The services delivered by a plurality of providers (SP) towards the users (U) are identified by respective streams of encoded data, for instance MPEG data. The users (U) are provided with respective receiving means (STB) of a generalised type, common to all users. Each user is provided with a user unit (), preferably embodied in the form of a smart card, incorporating a processing function (VM) able to recognize, load and execute at least one enabling algorithm embedded in the data streams sent by the providers, by exploiting a respective identifying code, also embedded in the delivered data stream, to enable to receiving means, through the user unit (), to make use of the respective service.

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Turin, Italy

Massimo Balestri