Abstract: An image retrieval method comprising: a step of extracting at least one query feature vector from a query image on which a subject of the image retrieval is captured, the query feature vector representing a local feature of the query image; a step of accessing an image data base in which a plurality of reference images are stored previously, each reference image being stored in conjunction with learning images generated therefrom and reference feature vectors representing local features of the reference image and the learning images; a comparing step of comparing the query feature vector with the reference feature vectors stored in conjunction with each reference image using an approximate nearest neighbor search to find a reference feature vector approximately nearest to the query feature vector; and a selecting step of selecting a reference image with which the found reference feature vector is stored in conjunction from the reference images as a retrieval result wherein: the learning image is generated by

Abstract: The present application relates to a method whereby a plurality of characteristic vectors which are extracted from image data are logged in a database together with the image data for approximate nearest neighbor searching, and has as an objective reducing computation time and memory use. L groups of K hash tables are generated, and each characteristic vector is respectively logged with each hash table.

Abstract: A pattern recognition apparatus including: an extracting section for extracting, from a query image that is composed of at least one piece of pattern component and previously undergoes a geometric transformation, the pattern component; a feature acquiring section for acquiring a geometric invariant feature of the pattern component as a query feature, the query feature being represented by at least three feature points including first, second and third feature points, each feature point locating on the pattern component and being retrieved from the pattern component based on a predetermined rule; a comparing section for comparing the query feature with a plurality of reference features, each reference feature representing different reference patterns prepared as candidates for pattern recognition; and a pattern determination section for determining, as a recognition result, a specific reference pattern out of the candidates based on a similarity of features therebetween and, wherein: each reference feature is

Abstract: Provided is a method for constructing an image database for object recognition, which includes a feature extraction step of extracting local descriptors from object images which are to be stored in an image database, a scalar quantization step of quantizing a numeric value indicating each dimension of each of the local descriptors into a predetermined number of bit digits, and a storing step of organizing each of the local descriptors after the quantization to be able to be searched for in the closest vicinity, giving to the local descriptor an identifier of the image from which the local descriptor has been extracted, and storing the local descriptor to which the identifiers are given in the image database.

Abstract: A pattern recognition apparatus including: an extracting section for extracting, from a query image that is composed of at least one piece of pattern component and previously undergoes a geometric transformation, the pattern component; a feature acquiring section for acquiring a geometric invariant feature of the pattern component as a query feature, the query feature being represented by at least three feature points including first, second and third feature points, each feature point locating on the pattern component and being retrieved from the pattern component based on a predetermined rule; a comparing section for comparing the query feature with a plurality of reference features, each reference feature representing different reference patterns prepared as candidates for pattern recognition; and a pattern determination section for determining, as a recognition result, a specific reference pattern out of the candidates based on a similarity of features therebetween and, wherein: each reference feature is

Abstract: For object recognition based on nearest neighbor search of local descriptors such as SIFT, it is important to keep the nearest neighbor search efficient to deal with a huge number of descriptors. The present invention provides methods of efficient recognition. In one embodiment, the method is based on the observation that the level of accuracy of nearest neighbor search for correct recognition depends on images to be recognized. The method is characterized by the mechanism that multiple recognizers with approximate nearest neighbor search are cascaded in the order of the level of approximation so as to improve the efficiency by adaptively controlling the level to be applied depending on images. In another embodiment the method is characterized by excluding local descriptors with low discriminability when a plenty of local descriptors are present in the vicinity and a plenty of distance calculation are required.

Abstract: An image retrieval method comprising: a step of extracting at least one query feature vector from a query image on which a subject of the image retrieval is captured, the query feature vector representing a local feature of the query image; a step of accessing an image data base in which a plurality of reference images are stored previously, each reference image being stored in conjunction with learning images generated therefrom and reference feature vectors representing local features of the reference image and the learning images; a comparing step of comparing the query feature vector with the reference feature vectors stored in conjunction with each reference image using an approximate nearest neighbor search to find a reference feature vector approximately nearest to the query feature vector; and a selecting step of selecting a reference image with which the found reference feature vector is stored in conjunction from the reference images as a retrieval result wherein: the learning image is generated by

Abstract: A document/image retrieval method for retrieving a document/image corresponding to a captured digital image from a database by comparing features calculated based on feature points of the captured digital image with features preliminarily calculated based on feature points of each of documents and/or images stored in the database, the method comprising: extracting the feature points from the captured digital image; defining a local set of feature points for each of the extracted feature points; selecting feature points from the defined local set to define a feature point subset of the local set; determining invariant values as values characterizing the defined subset for combinations of the feature points in the subset, the invariant values being invariant to a geometric transformation; calculating a feature by combining the determined invariant values; and performing a voting process on the documents and/or images in the database based on the preliminarily calculated features of the documents and/or images;

Abstract: Provided is a method for constructing an image database for object recognition, which includes a feature extraction step of extracting local descriptors from object images which are to be stored in an image database, a scalar quantization step of quantizing a numeric value indicating each dimension of each of the local descriptors into a predetermined number of bit digits, and a storing step of organizing each of the local descriptors after the quantization to be able to be searched for in the closest vicinity, giving to the local descriptor an identifier of the image from which the local descriptor has been extracted, and storing the local descriptor to which the identifiers are given in the image database.

Abstract: The invention provides a method for actualizing a high-speed object recognition process in an object recognition which extracts feature vectors from an input image where an object is captured, the feature vectors representing the object with the large number of the feature vectors; and retrieves, among an image database, one or more images whose features are matched. The invention also provides a method for saving a memory capacity required for the image database. Suggested are methods each of the methods being capable of reducing a processing time required to perform a task which recognizes the object described by a plurality of the feature vectors with use of an approximate nearest neighbor search technique. One of the suggested methods is actualized by excluding such feature vectors that a large number of feature vectors are present in the vicinity and a large number of distance calculations, therefore, are required.

Abstract: A document/image retrieval method for retrieving a document/image corresponding to a captured digital image from a database by comparing features calculated based on feature points of the captured digital image with features preliminarily calculated based on feature points of each of documents and/or images stored in the database, the method comprising: extracting the feature points from the captured digital image; defining a local set of feature points for each of the extracted feature points; selecting feature points from the defined local set to define a feature point subset of the local set; determining invariant values as values characterizing the defined subset for combinations of the feature points in the subset, the invariant values being invariant to a geometric transformation; calculating a feature by combining the determined invariant values; and performing a voting process on the documents and/or images in the database based on the preliminarily calculated features of the documents and/or images;