Providing security for webservers against unwanted and automated registrations has become a big concern. To prevent these kinds of false registrations many websites use CAPTCHAs. Among all kinds of CAPTCHAs OCR-Based or visual CAPTCHAs are very common. Actually visual CAPTCHA is an image containing a sequence of characters. So far most of visual CAPTCHAs, in order to resist against OCR programs...

The paper analyzes the interaction between humans and computers in terms of response time in solving the image-based CAPT-CHA. In particular, the analysis focuses on the attitude of the different Internet users in easily solving four different types of image-based CAPTCHAs which include facial expressions like: animated character, old woman, surprised face, worried face. To pursue this goal, an...

For the last ten years, CAPTCHAs have been widely used by websites to prevent their data being automatically updated by machines. By supposedly allowing only humans to do so, CAPTCHAs take advantage of the reverse Turing test (TT), knowing that humans are more intelligent than machines. Generally, CAPTCHAs have defeated machines, but things are changing rapidly as technology improves. Hence, ad...

Social tagging has been applied to many applications including image sharing, bookmarking and music recommendations. We have developed a application for the social tagging of people to support contact management and browsing profiles in an enterprise directory. As we expected, we found that users tag people for personal organization and for “social” motivations just as in other systems. However...

In this paper, we examine computational approaches for measuring the "fairness" of image tagging systems, finding that they cluster into five distinct categories, each with its own analytic foundation. We also identify a range normative concerns are often collapsed under terms "unfairness," "bias," or even "discrimination" when discussing problematic cases tagging. Specifically, four types repr...

This paper describes a new method for the automated segmentation and extraction of cardiac MRI tagging lines. Our method is based on the novel use of a 2D Gabor filter bank. By convolving the tagged input image with our Gabor filters, the tagging lines are automatically enhanced and segmented out. We design the Gabor filter bank based on the input image’s spatial and frequency characteristics. ...

Optical character recognition (OCR) is one of the fundamental problems in artificial intelligence and image processing, but recent progress in OCR represents a security challenge for Web sites that throttle requests with image based CAPTCHAs (Completely Automated Public Turing Tests to Tell Computers and Humans Apart). A CAPTCHA is challengeresponse test placed within web forms to determine whe...