Local feature descriptor extracting apparatus, local feature descriptor extracting method, and program
First Claim
1. A local feature descriptor extracting apparatus comprising:
- a memory that stores a program; and
a processor configured to run the program stored in the memory that is configured to cause the processor todetect a plurality of feature points in an image and output feature point information that is information regarding each feature point,select a prescribed number of feature points in a descending order of scale from the plurality of detected feature points, based on the feature point information,acquire a local region corresponding to each selected feature point,divide each local region into a plurality of subregions,generate a feature vector of a plurality of dimensions for each subregion in each local region, andselect a dimension from the feature vector for each subregion so that at least one gradient direction differs between neighboring subregions, based on a positional relationship between subregions in each local region and output an element of the selected dimension as a feature descriptor of the local region.
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Abstract
An object of the present invention is to reduce a size of a feature descriptor while maintaining accuracy of object identification. A local feature descriptor extracting apparatus includes: a feature point detecting unit which detects a plurality of feature points in an image and which outputs feature point information that is information regarding each feature point; a feature point selecting unit which selects a prescribed number of feature points in an order of importance from the plurality of detected feature points, based on the feature point information; a local region acquiring unit which acquires a local region corresponding to each selected feature point; a subregion dividing unit which divides each local region into a plurality of subregions; a subregion feature vector generating unit which generates a feature vector of a plurality of dimensions for each subregion in each local region; and a dimension selecting unit which selects a dimension from the feature vector for each subregion so that a correlation between neighboring subregions is lowered, based on a positional relationship between subregions in each local region and which outputs an element of the selected dimension as a feature descriptor of the local region.
4 Citations
10 Claims
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1. A local feature descriptor extracting apparatus comprising:
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a memory that stores a program; and a processor configured to run the program stored in the memory that is configured to cause the processor to detect a plurality of feature points in an image and output feature point information that is information regarding each feature point, select a prescribed number of feature points in a descending order of scale from the plurality of detected feature points, based on the feature point information, acquire a local region corresponding to each selected feature point, divide each local region into a plurality of subregions, generate a feature vector of a plurality of dimensions for each subregion in each local region, and select a dimension from the feature vector for each subregion so that at least one gradient direction differs between neighboring subregions, based on a positional relationship between subregions in each local region and output an element of the selected dimension as a feature descriptor of the local region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A local feature descriptor extracting method for causing a computer to:
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detect a plurality of feature points in an image and output feature point information that is information regarding each feature point; select a prescribed number of feature points in a descending order of scale from the plurality of detected feature points, based on the feature point information; acquire a local region corresponding to each selected feature point; divide each local region into a plurality of subregions; generate a feature vector of a plurality of dimensions for each subregion in each local region; and select a dimension from the feature vector for each subregion so that at least one gradient direction differs between neighboring subregions is lowered, based on a positional relationship between subregions in each local region, and output an element of the selected dimension as a feature descriptor of the local region.
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10. A non-transitory computer-readable storage medium storing a program for causing a computer to realize the functions of:
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detecting a plurality of feature points in an image and outputting feature point information that is information regarding each feature point; selecting a prescribed number of feature points in a descending order of scale from the plurality of detected feature points, based on the feature point information; acquiring a local region corresponding to each selected feature point; dividing each local region into a plurality of subregions; generating a feature vector of a plurality of dimensions for each subregion in each local region; and selecting a dimension from the feature vector for each subregion so that at least one gradient direction differs between neighboring subregions is lowered, based on a positional relationship between subregions in each local region, and outputting an element of the selected dimension as a feature descriptor of the local region.
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Specification