Patent ID: 6301388
Filing Date: 2001-10-09
Classification: G06K

Abstract:
An image matching apparatus for judging whether a first two-dimensional image and a second two-dimensional image match, the first two-dimensional image and the second two-dimensional image each being made up of a plurality of sets of pixel data in a two-dimensional xy coordinate plane, the image matching apparatus comprising:first two-dimensional vector group storing means for storing a plurality of two-dimensional vectors Va which are generated using a plurality of sets of pixel data of the first two-dimensional image and which respectively correspond to a plurality of positions in the first two-dimensional image, each of the plurality of two-dimensional vectors Va including a component relating to an x direction and a component relating to a y direction to show a feature, among a plurality of features of the first two-dimensional image, that is present in a corresponding position, wherein the x component and they component respectively are a spatial gradient of a value of a set of pixel data in the x direction and a spatial gradient of the value of the set of pixel data in the y direction;second two-dimensional vector group storing means for storing a plurality of two-dimensional vectors Vb which are generated using a plurality of sets of pixel data of the second two-dimensional image and which respectively correspond to a plurality of positions in the second two-dimensional image, each of the plurality of two-dimensional vectors Vb including a component relating to the x direction and a component relating to the y direction to show a feature, among a plurality of features of the second two-dimensional image, that is present in a corresponding position, wherein the x component and they component respectively are a spatial gradient of a value of a set of pixel data in the x direction and a spatial gradient of the value of the set of the pixel data in the y direction; andmatching means for judging that the first two-dimensional image and the second two-dimensional image match, when a distribution of the plurality of two-dimensional vectors Va stored in said first two-dimensional vector group storing means in the two dimensional xy coordinate plane and a distribution of the plurality of two-dimensional vectors Vb stored in said second two dimensional vector group storing means in the two-dimensional xy coordinate plane satisfy predetermined matching conditions, wherein said matching means includes:a first reference specifying unit for specifying one of the plurality of positions in the first two-dimensional image as a first position;a second reference specifying unit for specifying one of the plurality of positions in the second two-dimensional image as a second position;a first three-dimensional vector group generating unit for generating, for each respective position of the plurality of positions in the first two-dimensional image aside from the first position, a three-dimensional vector Ra composed of a component r, a component .alpha., and a component .beta., the component r being a magnitude of a two-dimensional vector Roa which directs from the first position to the respective position, the component .alpha. being an angle which the two-dimensional vector Roa forms with a two-dimensional vector Va present in the first position, and the component .beta. being an angle which a two-dimensional vector Va present in the respective position forms with the two-dimensional vector Va present in the first position;a second three-dimensional vector group generating unit for generating, for each respective position of the plurality of positions in the second two-dimensional image aside from the second position, a three-dimensional vector Rb composed of a component r, a component .alpha., and a component .beta., the component r being a magnitude of a two-dimensional vector Rob which directs from the second position to the respective position, the component .alpha. being an angle which the two-dimensional vector Rob forms with a two-dimensional vector Vb present in the second position, and the component .beta. being an angle which a two-dimensional vector Vb present in the respective position forms with the two-dimensional vector Vb present in the second position; anda first judging unit for judging that the predetermined matching conditions are satisfied and accordingly the first two-dimensional image and the second two-dimensional image match, when in a distribution of a plurality of three-dimensional vectors Ra generated by said first three-dimensional vector group generating unit and in a distribution of a plurality of three-dimensional vectors Rb generated by said second three-dimensional vector group generating unit, components .alpha. and components .beta. of the plurality of three-dimensional vectors Ra match components .alpha. and components .beta. of the plurality of three-dimensional vectors Rb to a first predetermined degree, and components r of the plurality of three-dimensional vectors Ra are proportional to components r of the plurality of three-dimensional vectors Rb to a second predetermined degree.