LOWER ORDER CIRCLE AND ELLIPSE HOUGH TRANSFORM

In this work we present two new algorithms for the detection of circle s and ellipses which use the FHT algorithm as a basis: Fast Circle Hou gh Transform (FCHT) and Fast Ellipse Hough Transform (FEHT). The first stage of these two algorithms, devoted to obtaining the centers of th e figures, is computationally the most costly. With the objective of i mproving the execution times of this stage it has been implemented usi ng a new focusing algorithm instead of the typical polling process in a parameter space. This new algorithm uses a new strategy that manages to reduce the execution times, especially in the case where multiple figures appear in the image, or when they are of very different sizes. We also perform a labeling of the image points that permits discrimin ating which of these belong to each figure, saving computations in sub sequent stages. (C) 1997 Pattern Recognition Society. Published by Els evier Science Ltd.