A Completely Automated Public Turing test to tell Computer and Humans Apart (CAPTCHA) is a variation of the Turing test, in which a challenge is used to distinguish humans from computers (‘bots’) on the internet. They are commonly used to prevent the abuse of online services; for example, malicious users have written automated programs that sign up for thousands of free email accounts and send SPAM messages. A number of hard artificial intelligence problems, including natural language processing, speech recognition, character recognition, and image understanding, have been used as the basis for these challenges on the expectation that humans will outperform bots. The most common type of CAPTCHA requires a user to transcribe distorted characters displayed within a noisy image. Unfortunately, many users find CAPTCHAs based on character-recognition frustrating and attack success rates as high as 60% have been reported for Microsoft’s Hotmail CAPTCHA [8].To address these problems, we present a first attempt at using content-based video labeling (‘tagging’) as a the basis for a CAPTCHA.

Date of creation, presentation, or exhibit



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Document Type

Conference Paper

Department, Program, or Center

Computer Science (GCCIS)


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