Distortion Estimation Techniques in Solving Visual CAPTCHAs

Abstract-- This paper describes two distortion estimation techniques for object recognition that solve EZ-Gimpy and Gimpy-r, two of the visual CAPTCHAs ("Completely Automated Public Turing test to tell Computers and Humans Apart") with high degrees of success. A CAPTCHA is a program that generates and grades tests that most humans can pass but current computer programs cannot pass. We have developed a correlation algorithm that correctly identifies the word in an EZ-Gimpy challenge image 99% of the time and a direct distortion estimation algorithm that correctly identifies the four letters in a Gimpy-r challenge image 78% of the time.

• Type: Conference
• Year: 2004
• Where: CVPR
• Authors: Gabriel Moy, Nathan Jones, Curt Harkless, Randall Potter
• Keywords: Challenge Image, Computer Vision, CVPR 2004, Distortion Estimation Algorithm, Distortion Estimation Techniques, EZ-Gimpy Challenge Image, Gimpy-r Challenge Image