Robust localization and identification of African clawed frogs in digital images

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Tek F. B., Cannavo F., Nunnari G., Kale I.

ECOLOGICAL INFORMATICS, vol.23, pp.3-12, 2014 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 23
  • Publication Date: 2014
  • Doi Number: 10.1016/j.ecoinf.2013.09.005
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.3-12
  • Keywords: Xenopus laevis, Automated frog identification, Skin pattern recognition, Area granulometry, SIFT, HoG, TEXTURE, CLASSIFICATION, RETRIEVAL
  • Istanbul Technical University Affiliated: No


We study the automatic localization and identification of African clawed frogs (Xenopus laevis sp.) in digital images taken in a laboratory environment. We propose a novel and stable frog body localization and skin pattern window extraction algorithm. We show that it compensates scale and rotation changes very well. Moreover, it is able to localize and extract highly overlapping regions (pattern windows) even in the cases of intense affine transformations, blurring, Gaussian noise, and intensity transformations. The frog skin pattern (i.e. texture) provides a unique feature for the identification of individual frogs. We investigate the suitability of five different feature descriptors (Gabor filters, area granulometry, HoG,(1) dense SIFT,(2) and raw pixel values) to represent frog skin patterns. We compare the robustness of the features based on their identification performance using a nearest neighbor classifier. Our experiments show that among five features that we tested, the best performing feature against rotation, scale, and blurring modifications was the raw pixel feature, whereas the SIFT feature was the best performing one against affine and intensity modifications. (C) 2013 Elsevier B.V. All rights reserved.