Using Character Recognition and Segmentation to Tell Computer from Humans

  • Authors:
  • Patrice Y. Simard;Richard Szeliski;Josh Benaloh;Julien Couvreur;Iulian Calinov

  • Affiliations:
  • -;-;-;-;-

  • Venue:
  • ICDAR '03 Proceedings of the Seventh International Conference on Document Analysis and Recognition - Volume 1
  • Year:
  • 2003

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Abstract

How do you tell a computer from a human? Thesituation arises often on the Internet, when online pollsare conducted, accounts are requested, undesired email isreceived, and chat-rooms are spammed. The approachwe use is to create a visual challenge that is easy forhumans but difficult for a computer. More specifically,our challenge is to recognize a string of randomdistorted characters. To pass the challenge, the subjectmust type in the correct corresponding ASCII string.From an OCR point of view, this problem is interestingbecause our goal is to use the vast amount ofaccumulated knowledge to defeat the state of the art OCRalgorithms. This is a role reversal from traditional OCRresearch.Unlike many other systems, our algorithm is based onthe assumption that segmentation is much more difficultthan recognition. Our image challenges present hardsegmentation problems that humans are particularly aptat solving. The technology is currently being used inMSN's Hotmail registration system, where it hassignificantly reduced daily registration rate with minimalConsumer Support impact.