Information Retrieval Using Invisible Junctions and Geometric Constraints
First Claim
1. A method for retrieving an electronic document using invisible junction features, the method comprising:
- receiving an image of an input electronic document;
extracting an invisible junction feature descriptor from the image; and
retrieving information for an output electronic document using the invisible junction feature descriptor and a geometric constraint.
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Abstract
The present invention uses invisible junctions which are a set of local features unique to every page of the electronic document to match the captured image to a part of an electronic document. The present invention includes: an image capture device, a feature extraction and recognition system and database. When an electronic document is printed, the feature extraction and recognition system captures an image of the document page. The features in the captured image are then extracted, indexed and stored in the database. Given a query image, usually a small patch of some document page captured by a low resolution image capture device, the features in the query image are extracted and compared against those stored in the database to identify the query image. The present invention advantageously uses geometric estimation to reduce the query results to a single one or a few candidate matches. In one embodiment, the two separate geometric estimations are used to rank and verify matching candidates.
115 Citations
26 Claims
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1. A method for retrieving an electronic document using invisible junction features, the method comprising:
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receiving an image of an input electronic document; extracting an invisible junction feature descriptor from the image; and retrieving information for an output electronic document using the invisible junction feature descriptor and a geometric constraint. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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- 11. The method of claim 11, wherein the ranking the plurality of output electronic documents using the first geometric constraint to produce the first ranking uses feature detection with geometric constraints.
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13. A system for retrieving an electronic document using invisible junction features, the system comprising:
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a feature extraction unit having an input and an output for producing an invisible junction feature descriptor from an image, the input of the feature extraction unit coupled to receive an input image; and a feature retrieval unit having an input and an output for retrieving information about an output electronic document using the invisible junction feature descriptor and a geometric constraint, the input of the feature retrieval unit coupled to the output of the feature extraction unit, the output of the feature retrieval unit providing the information about the output electronic document. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification