Computer Vision and Image Understanding, ( ISI ), Volume (113), No (4), Year (2009-4) , Pages (556-564)

Title : ( Omnidirectional edge detection )

Authors: Kamaledin Ghiasi Shirazi , Reza Safabakhsh ,

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In this paper we propose a new method for extending 1-D step edge detection filters to two dimensions via complex-valued filtering. Complex-valued filtering allows us to obtain edge magnitude and direction simultaneously. Our method can be viewed either as an extension of n-directional complex filtering of Paplinski to infinite directions or as a variant of Canny’s gradient-based approach. In the second view, the real part of our filter computes the gradient in the x direction and the imaginary part computes the gradient in the y direction. Paplinski claimed that n-directional filtering is an improvement over the gradient-based method, which computes gradient only in two directions. We show that our omnidirectional and Canny’s gradient-based extensions of the 1-D DoG coincide. In contrast to Paplinski’s claim, this coincidence shows that both approaches suffer from being confined to the subspace of two 2-D filters, even though n-directional filtering hides these filters in a single complex-valued filter. Aside from these theoretical results, the omnidirectional method has practical advantages over both n-directional and gradient-based approaches. Our experiments on synthetic and real-world images show the superiority of omnidirectional and gradient-based methods over n-directional approach. In comparison with the gradient-based method, the advantage of omnidirectional method lies mostly in freeing the user from specifying the smoothing window and its parameter. Since the omnidirectional and Canny’s gradient-based extensions of the 1-D DoG coincide, we have based our experiments on extending the 1-D Demigny filter. This filter has been proposed by Demigny as the optimal edge detection filter in sampled images.


, Complex-valued filtering, Directional edge detection, Infinite directional, Two-dimensional edge detection
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author = {Ghiasi Shirazi, Kamaledin and Reza Safabakhsh},
title = {Omnidirectional edge detection},
journal = {Computer Vision and Image Understanding},
year = {2009},
volume = {113},
number = {4},
month = {April},
issn = {1077-3142},
pages = {556--564},
numpages = {8},
keywords = {Complex-valued filtering; Directional edge detection; Infinite directional; Two-dimensional edge detection},


%0 Journal Article
%T Omnidirectional edge detection
%A Ghiasi Shirazi, Kamaledin
%A Reza Safabakhsh
%J Computer Vision and Image Understanding
%@ 1077-3142
%D 2009