Abstract: In order to define the contour of an ellipse, it is necessary to determine five unknown parameters in the general equation representative of centered conics. When directly applying Hough transformation method to the above equation, since a five-dimensional space is required, it is practically impossible to detect an ellipse because a long processing time and a great amount of memory capacity are inevitably required. To overcome these problems, the geometric properties of an ellipse are determined separately on three parameter sub-spaces obtained on the basis of edge vector field: two-dimensional center histogram and two-dimensional (H, B) histogram, one-dimensional C histogram. A peak value on the center histogram represents a group of ellipse having the same center locations; a peak value on the (H, B) histogram represents a group of concentric ellipse having the same eccentricity and axis slope; a peak value on the C histogram defines a single ellipse.
January 19, 1984
Date of Patent:
October 21, 1986
Michio Kawata, Director-General of Agency of Industrial Science and Technology, Kabushiki Kaisha Meidensha