Feature extraction system and face image recognition system
First Claim
1. A feature extraction system for statistically analyzing a set of samples of feature vectors to calculate an amount indicative of a feature which plays an important role when pattern-identification is performed, said system comprising:
- feature vector input means for inputting a feature vector;
storage means for storing said feature vector inputted through said input means;
neighborhood vector selection means for selecting a neighborhood vector, being a feature vector close to said feature vector inputted and stored in said storage means, from feature vectors existing in said storage means; and
feature vector space production means for outputting a partial vector space in which feature vectors locally most disperse when said feature vectors are orthogonally projected thereinto,wherein, when said feature vectors stored in said storage means are taken to be Vi (1≦
i≦
N) and the dimension of these feature vectors is taken as n, said neighbor vector selection means selects M (≦
N) feature vectors close to these feature vectors through the use of a distance d(x, y), where x and y represent feature vectors, determined according to the following equation (1);
##EQU16## and said feature vector space production means obtains eigenvectors by solving an eigenvalue problem of a local covariance matrix given from the following equation (2);
##EQU17## where Vj.sup.(i) denotes a neighborhood vector to Vi and n(i) depicts the total number of possible Vj.sup.(i) which varies at every i, moreover, said feature vector space production means selects m (≦
N, n) eigenvectors from the obtained eigenvectors in the order of decreasing corresponding eigenvalue to output them as bases of a partial vector space which maximizes a local scattering property.
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Abstract
A feature extraction system for statistically analyzing a set of samples of feature vectors to calculate a feature being an index for a pattern identification, which is capable of identifying confusing data with a high robustness. In this system, a storage section stores a feature vector inputted through an input section and a neighborhood vector selection section selects a specific feature vector from the feature vectors existing in the storage section. The specific feature is a neighborhood vector close in distance to the feature vector stored in the storage section. Further, the system is equipped with a feature vector space production section for outputting a partial vector space. The partial vector space is made to maximize the local scattering property of the feature vector when the feature vector is orthogonally projected to that space.
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Citations
11 Claims
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1. A feature extraction system for statistically analyzing a set of samples of feature vectors to calculate an amount indicative of a feature which plays an important role when pattern-identification is performed, said system comprising:
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feature vector input means for inputting a feature vector; storage means for storing said feature vector inputted through said input means; neighborhood vector selection means for selecting a neighborhood vector, being a feature vector close to said feature vector inputted and stored in said storage means, from feature vectors existing in said storage means; and feature vector space production means for outputting a partial vector space in which feature vectors locally most disperse when said feature vectors are orthogonally projected thereinto, wherein, when said feature vectors stored in said storage means are taken to be Vi (1≦
i≦
N) and the dimension of these feature vectors is taken as n, said neighbor vector selection means selects M (≦
N) feature vectors close to these feature vectors through the use of a distance d(x, y), where x and y represent feature vectors, determined according to the following equation (1);
##EQU16## and said feature vector space production means obtains eigenvectors by solving an eigenvalue problem of a local covariance matrix given from the following equation (2);
##EQU17## where Vj.sup.(i) denotes a neighborhood vector to Vi and n(i) depicts the total number of possible Vj.sup.(i) which varies at every i, moreover, said feature vector space production means selects m (≦
N, n) eigenvectors from the obtained eigenvectors in the order of decreasing corresponding eigenvalue to output them as bases of a partial vector space which maximizes a local scattering property. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A face image recognition system comprising:
- model face image input means for receiving a model face image;
first feature extraction means for extracting a feature from said model face image; first model feature vector holding means for holding a result of the feature extraction obtained when said first feature extraction means extracts said feature from said face image inputted through said model face image input means; first and second model limitation means for taking a set of models having feature vectors satisfying a given condition on the variation from a feature vector of each of the model face images; model eigenspace holding means for calculating the greatest to Nth eigenvalues of eigenvalues of a scattering property evaluation matrix defined by the following equation (8) in relation to said set of model faces limited by said first model limitation means and eigenvectors corresponding to the greatest to Nth eigenvalues and further for holding these calculation results at every model, ##EQU23## where Mi represents the ith model face vector, Mij designates the jth model face vector belonging to the neighborhood of said model Mi, NM denotes the total number of model face images, NMi depicts the number of models belonging to the neighborhood of said model Mi, and T signifies the transposition of a matrix (vector); object face image input means for receiving an object face image under recognition; second feature extraction means for extracting a feature from said face image; first object image feature vector holding means for holding a feature vector extracted by said second feature extraction means from said object face image inputted through said object face image input means; second model feature vector holding means for holding a feature vector extracted by said first feature extraction means from each of the model face images inputted through said model face image input means; first model selection means for finding a model feature vector of the model feature vectors held in said second model feature vector holding means, said model feature vector to be found showing a minimum variation with respect to the object image feature vector; and second model selection means for selecting a model face vector from among the model face vectors M selected by said first model selection means and limited by said second model limitation means, said model face vector to be selected being a vector by which variation of a point m obtainable in a manner of being projected onto a space defined by N eigenvectors Ej (j=1 . . . N) held in said model eigenspace holding means according to the following equation (9) with respect to a point i of the object face vector I projected to the same space according to the same equation (9) stands at a minimum,
space="preserve" listing-type="equation">m=(m.sub.1, m.sub.2, . . . ,m.sub.N)
space="preserve" listing-type="equation">i=(i.sub.1, i.sub.2, . . . ,i.sub.N)
space="preserve" listing-type="equation">m.sub.k =(E.sub.k, M)
space="preserve" listing-type="equation">i.sub.l =(E.sub.l, I) (9)where mk and il respectively denote the kth and lth coordinate values on the projection of said model face vector M and an object face vector I to an eigenspaces, and (a,b) depicts the inner product of vectors a and b. - View Dependent Claims (8, 9, 10, 11)
- model face image input means for receiving a model face image;
Specification