Patent ID: 8363981
Filing Date: 2013-01-29
Classification: G06T

Abstract:
1. An image converter for performing processes of cutting out a part of a distorted circular image photographed by use of a fisheye lens and converting it into a planar regular image, the image converter comprising: a distorted circular image storage unit which stores a distorted circular image constituted with aggregates of pixels arranged at a position indicated by coordinates (x, y) on a two-dimensional XY orthogonal coordinate system and having a radius R taking an origin O of the XY coordinate system as a center; a planar regular image storage unit which stores a planar regular image constituted with aggregates of pixels arranged at a position indicated by coordinates (u, v) on a two-dimensional UV orthogonal coordinate system; a distorted circular image display unit which displays the distorted circular image stored in the distorted circular image storage unit; an instruction input unit which inputs a position of a cut-out center point P and a cut-out orientation on the distorted circular image displayed on the basis of instructions by a user; an intersecting point operation unit which, when a virtual sphere having a radius R taking the origin O as a center is defined in a three-dimensional XYZ orthogonal coordinate system including the two-dimensional XY orthogonal coordinate system, determines position coordinates (x an angle determining unit which determines on the basis of the cut-out orientation a planar inclination angle φ given as an angle formed between a vector U facing an U axis of the two-dimensional UV orthogonal coordinate system which is defined on a tangent plane in contact with the virtual sphere at the intersecting point G and a vector X facing an X axis of the two-dimensional XY orthogonal coordinate system; and a transformation unit which makes correspondence between coordinates (u, v) and coordinates (x, y) by utilizing transformation equations based on an orthogonal projection method including the position coordinates (x wherein the instruction input unit has a function of entering instructions for defining a reference straight line J drawn on the distorted circular image, and the angle determining unit determines the planar inclination angle φ on the basis of an angle θ formed between the reference straight line J and the X axis (on the condition that θ=0° where both of them are parallel).