Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Array Processing and Fast Optimization Algorithms for Distorted Circular Contour Retrieval | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 57354 13 pages doi 2007 57354 Research Article Array Processing and Fast Optimization Algorithms for Distorted Circular Contour Retrieval Julien Marot and Salah Bourennane GSM Institut Fresnel CNRS-UMR 6133 Ecole Centrale Marseille Universite Aix-Marseille III D. U. de Saint Jerome 13397 Marseille Cedex20 France Received 19 July 2006 Revised 20 December 2006 Accepted 17 February 2007 Recommended by Wilfried Philips A specific formalism for virtual signal generation permits to transpose an image processing problem to an array processing problem. The existing method for straight-line characterization relies on the estimation of orientations and offsets of expected lines. This estimation is performed thanks to a subspace-based algorithm called subspace-based line detection SLIDE . In this paper we propose to retrieve circular and nearly circular contours in images. We estimate the radius of circles and we extend the estimation of circles to the retrieval of circular-like distorted contours. For this purpose we develop a new model for virtual signal generation we simulate a circular antenna so that a high-resolution method can be employed for radius estimation. An optimization method permits to extend circle fitting to the segmentation of objects which have any shape. We evaluate the performances of the proposed methods on hand-made and real-world images and we compare them with generalized Hough transform GHT and gradient vector flow GVF . Copyright 2007 J. Marot and S. Bourennane. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION Circular features in digital images are sought very often in digital image processing. An image containing one or several contours is composed of black .
