The circlet transform: A robust tool for detecting features with circular shapes

  • Authors:
  • H. Chauris;I. Karoui;P. Garreau;H. Wackernagel;P. Craneguy;L. Bertino

  • Affiliations:
  • Centre de Géosciences, Mines ParisTech, 35 rue Saint-Honoré, 77300 Fontainebleau, France and UMR-Sisyphe 7619, UPMC, Paris, France;Centre de Géosciences, Mines ParisTech, 35 rue Saint-Honoré, 77300 Fontainebleau, France and Ifremer, Plouzané, France;Ifremer, Plouzané, France;Centre de Géosciences, Mines ParisTech, 35 rue Saint-Honoré, 77300 Fontainebleau, France;Actimar, Brest, France;Nersc, Bergen, Norway

  • Venue:
  • Computers & Geosciences
  • Year:
  • 2011

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Abstract

We present a novel method for detecting circles on digital images. This transform is called the circlet transform and can be seen as an extension of classical 1D wavelets to 2D; each basic element is a circle convolved by a 1D oscillating function. In comparison with other circle-detector methods, mainly the Hough transform, the circlet transform takes into account the finite frequency aspect of the data; a circular shape is not restricted to a circle but has a certain width. The transform operates directly on image gradient and does not need further binary segmentation. The implementation is efficient as it consists of a few fast Fourier transforms. The circlet transform is coupled with a soft-thresholding process and applied to a series of real images from different fields: ophthalmology, astronomy and oceanography. The results show the effectiveness of the method to deal with real images with blurry edges.