creators_name: Gossweiler, Rich creators_name: Kamvar, Maryam creators_name: Baluja, Shumeet type: conference_item datestamp: 2009-04-06 19:11:08 lastmod: 2009-04-07 14:02:37 metadata_visibility: show title: What's Up CAPTCHA? A CAPTCHA Based on Image Orientation ispublished: pub full_text_status: public pres_type: paper abstract: We present a new CAPTCHA which is based on identifying an image’s upright orientation. This task requires analysis of the often complex contents of an image, a task which humans usually perform well and machines generally do not. Given a large repository of images, such as those from a web search result, we use a suite of automated orientation detectors to prune those images that can be automatically set upright easily. We then apply a social feedback mechanism to verify that the remaining images have a human-recognizable upright orientation. The main advantages of our CAPTCHA technique over the traditional text recognition techniques are that it is language-independent, does not require text-entry (e.g. for a mobile device), and employs another domain for CAPTCHA generation beyond character obfuscation. This CAPTCHA lends itself to rapid implementation and has an almost limitless supply of images. We conducted extensive experiments to measure the viability of this technique. date: 2009-04 pagerange: 841-841 event_title: 18th International World Wide Web Conference event_location: Madrid, Spain event_dates: April 20th-24th, 2009 event_type: conference refereed: TRUE citation: Gossweiler, Rich and Kamvar, Maryam and Baluja, Shumeet (2009) What's Up CAPTCHA? A CAPTCHA Based on Image Orientation. In: 18th International World Wide Web Conference, April 20th-24th, 2009, Madrid, Spain. document_url: http://www2009.eprints.org/85/1/p841.pdf