Captchas are in widespread use today, usually in the form of obscured or distorted text that people can still read. But there's a lot of work in the area, including identifying 3D images and distinguishing between cats and dogs.
Google has released research results which present a new Captcha which is based on indenting an image's upright orientation.
A persistent problem on the Internet is screening out automated computer systems that can be used, for example, to sign up for spam-sending e-mail accounts or post comments designed to improve a site's search results. Google, which already devotes a lot of resources to block e-mail and Web spam, has tried a new test to keep the bots at bay.
The test is the latest variation on a screening technique called a Captcha (completely automated public Turing test to tell computers and humans apart). The idea is that people can often tell which way is up in a photo, but computers have a harder time.
Summary:<>
<>Google authors Rich Gossweiler, Maryam Kamvar, and Shumeet Baluja described the image-orientation technique in their paper 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...Our Captcha technique achieves high success rates for humans and low success rates for bots, does not require text entry, and is more enjoyable for the user than text-based Captcha.
Finally<>:
Google present novel Captcha system that required to user to adjust randomly rotated images to their upright orientation.this task will be familiar to many people given use of the early use of digital camera,cell pone with camera or even the simple act of sorting through physical photographs.but it is also impotent that the images use for the captcha should carefully selected as many typical vacation or snapshots contain cues revelling upright orientation.
