CAPTCHA stands for Completely Automated Public Turing Test to Tell Computers and Human Apart. CAPTCHA is used for Internet Security specifically for accessing web sites. It is a Reverse Turing Test that identifies that the given problem is solved by a computer program or not. A number of CAPTCHA schemes are available today like, text-based, audio-based, video/animation-based, puzzle based etc. In this paper Image Based CAPTCHAs are collaborated at single place to analyze. The paper presents an extensive survey of Image Based CAPTCHA schemes from their generation to broken stage. Our target to review the literature is to identify and classify the existing literature on Image Based CAPTCHA, its types, the creation and breaking techniques. The paper puts light on the techniques that are used to generate these schemes and their limitations. The paper also discusses the effective methods for break these schemes.Modern classifiers such as Convolution Neural Networks and Dense Neural Networks are able to recognize image based data very effectively.

Image Based CAPTCHA,Bot Program, Reverse Turing Test.