San Francisco — After all these years, fending off bots from filling out forms automatically is a tedious task. Researchers at Google are have just released a report [PDF], which explores to find the perfect and more effective automated singups technique, which they call image orientation CAPTCHA.
Earlier, undoubtedly we have seen those jumbled up words that needed to decipher before you can submit a form well, that is still too easy for bots to figure out. But, the new test intends to foil computers pretending to be humans that now requires them to orient an image so it is upright.
A continuous difficulty over the Internet is analyzing automated computer systems that can be used, for example, CAPTCHA (or “Completely Automated Public Turing Test to Tell Computers and Humans Apart”) is employed to prevent automated signing up for spam-sending e-mail accounts or post comments designed to improve a site’s search results.
The report, called “What’s Up CAPTCHA?” describes the latest version, which uses image orientation, forcing a user to adjust randomly rotated images to their upright orientation. 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.
CAPTCHA (or “Completely Automated Public Turing Test to Tell Computers and Humans Apart”) is employed to prevent automated computer systems from signing up at sites or posting comments. The report, called "What’s Up CAPTCHA?" (PDF) outlines a new version, which uses image orientation, forcing a user to adjust randomly rotated images to their upright orientation.
Here is how Google authors Rich Gossweiler, Maryam Kamvar, and Shumeet Baluja described the image-orientation technique in their paper (click for PDF):
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.
Considering a large repository of images, such as those from a web search result, we employed 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 major benefits 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.
Google displayed 3 sample images below:
A
Google says this set is easy to orient upwards for humans, but bots may also succeed here because they may use face detection.
B
This is the most useful approach: for humans, adjusting to an upwards direction is easy, but for bots it’s not.
C
Sample C is again less useful because it’s hard for humans, too, to adjust this one correctly.
The researchers from Google explained that they performed extensive experiments to measure the viability of this technique… Our Captcha technique has achieved 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.
Below is an example interface, where one needs to slide 3 images into their “natural, upright positions”:
For comparison, a traditional text-based Captcha, as used in Google’s tests:
Nevertheless, sometimes the words are so distorted that it becomes so difficult to get it right on the first try … or second try … or … well, you get the drift. We find it extremely annoying when that happens.
According to Google, careful image selection means they would not have to distort the images, at least for now:
We ensure that our CAPTCHA can not be defeated by state-of-the-art orientation detection systems by using those systems to filter images that can be automatically recognized and oriented.