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55 results about "Orientation field" patented technology

Keypoint descriptor generation by complex wavelet analysis

ActiveUS20110262041A1Accurate and high quality object identificationImprove matchThree-dimensional object recognitionConsecutive frameComputer software
The present invention relates to a method of generating a keypoint descriptor for identifying an object in an image or in a sequence of images, the keypoint descriptor being substantially invariant to a transformation of the object in the image. The method includes receiving object data representing an object for identification in an image; processing said object data to generate at least one basis function representing a feature having undergone at least one transformation or a transformation sequence across several consecutive frames, optionally using transformations that are out of the image plane to recognise objects from multiple views; modifying a prototype wavelet function based on said at least one basis function to generate a plurality of modified wavelet functions; comparing the plurality of modified wavelet functions with the at least one basis function; selecting a modified wavelet function of said plurality of modified wavelet functions based on the comparison of the plurality of modified wavelet functions with the at least one basis function; and processing an input image or input orientation field according to said selected modified wavelet function to generate the keypoint descriptor. The present invention further relates to a method of identifying an object in an image using a keypoint descriptor; and apparatus and computer software for implementing a method in accordance with the present invention.
Owner:ZEBRA TECH CORP

Method for separating superimposed fingerprint images

The invention relates to a method for separating superimposed fingerprint images, which comprises the following steps: carrying out processing on a superimposed fingerprint image according to a fingerprint profile so as to obtain a background region image, a fingerprint superimposed region image and a single fingerprint region image; carrying out operation on the single fingerprint region image by using a gradient algorithm so as to obtain a first kind of fingerprint initial orientation field data, and carrying out operation on the fingerprint superimposed region image by using a local Fourier analysis algorithm so as to obtain a second type of fingerprint initial orientation field data, carrying out processing on the fingerprint initial orientation field data by using a loose labeling algorithm so as to obtain two types of rough fingerprint orientation field image files, and determining the optimal combination of fingerprint singular-points through a minimized original orientation field and a model-based orientation field reconstructed by the fingerprint singular-points; carrying out fingerprint orientation field reconstruction according to a hybrid model so as to obtain model-based fingerprint fine orientation field data; and carrying out processing on the model-based fingerprint fine orientation field data by using a filtering enhancement algorithm so as to obtain two fingerprint image files subjected to separation.
Owner:北京海鑫科金高科技股份有限公司

Preparation method for permanent-magnet material with high temperature resistance and high magnetic performance

The invention discloses a preparation method for a permanent-magnet material with high temperature resistance and high magnetic performance. The preparation method comprises the steps of 1) uniformly stirring and mixing Nd2Fe14B magnetic powder and graphene oxide powder to prepare mixed magnetic powder, mixing and adding a titanate coupling agent and an organic solvent into the mixed magnetic powder, mixing the product with ferrocene magnetic powder, performing drying, and performing vacuum drying and granulation after the dried mixed magnetic power and bisphenol A epoxy resin are mixed; and 2) forming the mixed magnetic powder obtained in the step 1) for 10-30 minutes in a composite environment of a temperature field with a constant temperature being 20-200 DEG C and an orientation field with magnetic field intensity being 0.5-3T so as to prepare the permanent-magnet material with high temperature resistance and high magnetic performance, wherein the formation pressure range is (2-8)ton/cm<2>. According to the method, the magnetic performance of a magnet is greatly improved by the permanent-magnet material, the weight loss of the magnet can be effectively reduced, and the corrosion resistance of the magnet is improved.
Owner:JIANGSU PULONG MAGNETIC ELECTRICITY CO LTD

Deformation finger print matching method based on curve coordinate system and transferred reference node

The invention discloses a deformed fingerprint matching method based on a curvilinear coordinate system and transference of reference minutiae. The method comprises the following steps: (1). a fingerprint image is represented that I(m*n),O(i, j) belonging to [0, pi) is the local ridge orientation at the pixel (i,j), and each minutia in the fingerprint image I is described by coordinate, direction and type; (2). X axis and Y axis of the curvilinear coordinate axes are extracted from each minutia by taking each minutia as an origin based on a ridge mode and an orientation field of the minutiae; (3). scales of the curvilinear coordinate axes are computed; (4). the coordinate relation between every two minutiae mi and mj are computed; and (5). The minutiae are matched by the method based on the transference of the reference minutiae: provided that a template fingerprint image T and an input fingerprint image Q contain p minutiae and q minutiae respectively, C(T) equals (Ci, j<T>), C(Q) equals (Ci, j<T>), wherein, i is not less than 0 and j is less than q; T and Q are matched by utilizing the minutiae of the C(T) and C(Q) pair to compute the matching minutiae. The method has the advantages of high identification accuracy rate, high efficiency and simple algorithm.
Owner:ZHEJIANG NORMAL UNIVERSITY

Method for Extracting Orientation Field of Markov Random Field Fingerprint Based on Prior Knowledge

The invention discloses a method for extracting a fingerprint direction field under a Morkov random field based on priori knowledge. The problems of incapability of accurately extracting fingerprint direction field information in a low-quality area and high generation rate of pseudo-singular point information in a model method in the prior art are mainly solved. The method is implemented by the following steps of: (1) inputting a fingerprint image, extracting the priori knowledge of a direction field of the fingerprint image, obtaining a block angle matrix of the fingerprint image by using a gradient method, and obtaining the probabilities of block angles by using a statistical method; (2) fitting the priori knowledge of the direction field, the obtained block angle matrix and the probabilities of the block angles, and constructing a priori-knowledge-based Morkov random field model of the fingerprint image; and (3) extracting a final direction field of the fingerprint image by using the constructed model. The priori knowledge of the fingerprint direction field is fitted on the basis of the conventional Morkov random field, and a new fingerprint direction field extraction model is constructed, so that the matching and retrieval performance of the fingerprint image are improved, and the method can be used for extracting the direction field of a low-quality fingerprint image.
Owner:XIDIAN UNIV
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