Usability Evaluation of Randomly Generated Fonts for Bubble Captcha

  • Ondrej Bostik
  • Karel Horak
  • Jan Klecka
Keywords: OCR, CAPTCHA, Neural Networks, k-NN, Decision trees, SVM, Bubble Captcha


A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA), is the wide-spread concept of systems suited to secure the web services from automated SPAM scripts. The most common CAPTCHA systems benefit from imperfections of Optical Character Recognition algorithms. This paper presents our ongoing work focused on the development of a new CAPTCHA scheme based on a human perception. The goal of this work is to evaluate the usability of randomly generated fonts used in Bubble Captcha scheme with both humans and OCR classifiers.


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How to Cite
Bostik, O., Horak, K. and Klecka, J. 2018. Usability Evaluation of Randomly Generated Fonts for Bubble Captcha. MENDEL. 24, 1 (Jun. 2018), 143-150. DOI:
Research articles