Detecting optic disc on asians by multiscale gaussian filtering

  • Authors:
  • Bob Zhang;Jane You;Fakhri Karray

  • Affiliations:
  • Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, Canada;Biometric Research Center, and Department of Computing, Hong Kong Polytechnic University, Hong Kong;Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, Canada

  • Venue:
  • Journal of Biomedical Imaging - Special issue on Advances in Computer-Aided Detection and Diagnosis
  • Year:
  • 2012

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Abstract

The optic disc (OD) is an important anatomical feature in retinal images, and its detection is vital for developing automated screening programs. Currently, there is no algorithm designed to automatically detect the OD in fundus images captured from Asians which are larger and have thicker vessels compared to Caucasians. In this paper, we propose such a method to complement current algorithms using two steps: OD vessel candidate detection and OD vessel candidate matching. The first step is achieved with multiscale Gaussian filtering, scale production, and double thresholding to initially extract the vessels' directional map of various thicknesses. The map is then thinned before another threshold is applied to remove pixels with low intensities. This result forms the OD vessel candidates. In the second step, a Vessels' DirectionalMatched Filter (VDMF) of various dimensions is applied to the candidates to be matched, and the pixel with the smallest difference designated the OD center. We tested the proposed method on a new database consisting of 402 images from a diabetic retinopathy (DR) screening programme consisting of Asians. The OD center was successfully detected with an accuracy of 99.25% (399/402).