Local feature descriptor extracting apparatus, method for extracting local feature descriptor, and program
First Claim
1. A local feature descriptor extracting apparatus comprising:
- memory that stores an image;
a processor configured to;
detect feature points in the image;
acquire a first local region for each of the feature points;
divide each first local region into a first plurality of subregions;
generate a first feature vector with a plurality of dimensions for each of the subregions in each first local region;
select dimensions from the first feature vector in each subregion such that at least one gradient orientation differs between proximate subregions and output elements of the selected dimensions as a feature descriptor of the first local region; and
store, in association with the image, the feature descriptor of each first local region of the image in the memory.
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Abstract
The size of a feature descriptor is reduced with the accuracy of object identification maintained. A local feature descriptor extracting apparatus includes a feature point detecting unit configured to detect feature points in an image, a local region acquiring unit configured to acquire a local region for each of the feature points, a subregion dividing unit configured to divide each local region into a plurality of subregions, a subregion feature vector generating unit configured to generate a feature vector with a plurality of dimensions for each of the subregions in each local region, and a dimension selecting unit configured to select dimensions from the feature vector in each subregion so as to reduce a correlation between the feature vectors in proximate subregions based on positional relations among the subregions in each local region and output elements of the selected dimensions as a feature descriptor of the local region.
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Citations
16 Claims
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1. A local feature descriptor extracting apparatus comprising:
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memory that stores an image; a processor configured to; detect feature points in the image; acquire a first local region for each of the feature points; divide each first local region into a first plurality of subregions; generate a first feature vector with a plurality of dimensions for each of the subregions in each first local region; select dimensions from the first feature vector in each subregion such that at least one gradient orientation differs between proximate subregions and output elements of the selected dimensions as a feature descriptor of the first local region; and store, in association with the image, the feature descriptor of each first local region of the image in the memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for extracting a local feature descriptor, the method performed by a processor in communication with memory comprising:
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retrieving an image from the memory; detecting feature points in an image; acquiring a local region for each of the feature points; dividing each local region into a plurality of subregions; generating a feature vector with a plurality of dimensions for each of the subregions in each local region; selecting dimensions from the feature vector in each subregion such that at least one gradient orientation differs between proximate subregions and outputting elements of the selected dimensions as a feature descriptor of the local region; and storing, in association with the image, the feature descriptor of each local region of the image in the memory.
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16. A non-transitory computer-readable storage medium storing a program for causing a computer to implement:
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a function of retrieving an image from memory; a function of detecting feature points in the image; a function of acquiring a local region for each of the feature points; a function of dividing each local region into a plurality of subregions; a function of generating a feature vector with a plurality of dimensions for each of the subregions in each local region; a function of selecting dimensions from the feature vector in each subregion such that at least one gradient orientation differs between proximate subregions and outputting elements of the selected dimensions as a feature descriptor of the local region; and a function of storing, in association with the image, the feature descriptor of each local region of the image in the memory.
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Specification