Normalized image feature processing
AssigneeBritish Telecommunications public limited company
InventorsMark Andrew Shackleton, William John Welsh
Life of this patent
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Abstract
A method of processing an image including the steps of: locating within the image the position of at least one predetermined feature; extracting from the image data representing each feature; and calculating for each feature a feature vector representing the position of the image data of the feature in an N-dimensional space, such space being defined by a plurality of reference vectors each of which is an eigenvector of a training set of like features in which the image data of each feature is modified to normalize the shape of each feature thereby to reduce its deviation from a predetermined standard shape of the feature, which step is carried out before calculating the corresponding feature vector.
Claims11
A method of processing an image represented by an array of digital signals, said method comprising the steps off
- locating within the image array of digital signals the position of at least one predetermined feature;
- extracting image data from said image array of digital signals representing each said feature;
- generating for each feature a feature vector digital signal representing the position of the image data of the feature in an N-dimensional space, N being an integer and said space being defined by a plurality of reference vector signals each of which is an eigenvector of a training set of images of like features;
- and
- modifying the digital signal image data of each feature to normalize the shape of each feature thereby to reduce its deviation from a predetermined standard shape of said feature, which step is carried out before generating the feature vector signal for each feature.
A method of processing an image represented by an array of digital signals, said method comprising the steps of:
- locating within the image array of digital signals the position of at least one predetermined feature;
- extracting image data from said image array of digital signals representing each said feature;
- generating for each feature a feature vector digital signal representing the position of the image data of the feature in an N-dimensional space, N being an integer and said space being defined by a plurality of reference vector signals each of which is an eigenvector of a training set of images of like features;
- and
- modifying the digital signal image data of each feature to normalize the shape of each feature thereby to reduce its deviation from a predetermined standard shape of said feature, which step is carried out before generating the feature vector signal for each feature,
- wherein the step of modifying the digital signal image data of each feature uses a deformable template.
A method of processing an image represented by an array of digital signals, said method comprising the steps of:
- locating within the image array of digital signals the position of at least one predetermined feature;
- extracting image data from said image array of digital signals representing each said feature;
- generating for each feature a feature vector digital signal representing the position of the image data of the feature in an N-dimensional space, N being an integer and said space being defined by a plurality of reference vector signals each of which is an eigenvector of a training set of images of like features;
- and
- modifying the digital signal image data of each feature to normalize the shape of each feature thereby to reduce its deviation from a predetermined standard shape of said feature, which step is carried out before generating the feature vector signal for each feature,
- wherein the step of locating within the digital signal image the position of at least one predetermined feature employs:
- a first technique to provide a coarse estimation of position, and
- a second, different, technique to improve upon the coarse estimation.
A method of verifying the identity of the user of a data carrier, said method comprising the steps of:
- generating a digital signal facial image of the user;
- receiving the data carrier and reading therefrom identification data signals;
- performing on the digital signal facial image the steps of:
- (i) locating within the digital signal image the position of at least one predetermined feature;
- (ii) extracting digital signal image data from said image representing each said feature;
- (iii) generating for each feature a feature vector signal representing the position of the image data of the feature in an N-dimensional space, N being an integer and said space being defined by a plurality of reference vectors signals each of which is an eigenvector of a training set of images of like features;
- and
- (iv) modifying the digital signal image data of each feature to normalize the shape of each feature thereby to reduce its deviation from a predetermined standard shape of said feature, which step is carried out before generating the feature vector for each feature;
- comparing data signals representing each feature vector with the identification data signals;
- and
- generating a verification signal in dependence upon the comparison.
Apparatus for verifying the identity of the user of a data carrier comprising:
- means for generating a digital signal facial image of the user;
- means for receiving the data carrier and reading therefrom identification data signals;
- means for performing on the digital signal facial image the steps of:
- (i) locating within the digital signal image and position of at least one predetermined feature;
- (ii) extracting digital signal image data from said image representing each said feature;
- (iii) generating for each feature a feature vector signal representing the position of the image data of the feature in an N-dimensional space, N being an integer and said space being defined by a plurality of reference vector signals each of which is an eigenvector of a training set of images of like features;
- and
- (iv) modifying the digital signal image data of each feature to normalize the shape of each feature thereby to reduce its deviation from a predetermined standard shape of said feature, which step is carried out before calculating the feature vector for each feature;
- and
- means for comparing data signals representing each feature vector with the identification data signals and generating a verification signal in dependence upon the comparison.
Dependencies are inferred from the claim text.