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Next-Generation CAPTCHA Exploits the Semantic Gap

Posted by kdawson on from the stand-and-identify dept.

captcha_fun writes "Researchers at Penn State have developed a patent-pending image-based CAPTCHA technology for next-generation computer authentication. A user is asked to pass two tests: (1) click the geometric center of an image within a composite image, and (2) annotate an image using a word selected from a list. These images shown to the users have fake colors, textures, and edges, based on a sequence of randomly-generated parameters. Computer vision and recognition algorithms, such as alipr, rely on original colors, textures, and shapes in order to interpret the semantic content of an image. Because of the endowed power of imagination, even without the correct color, texture, and shape information, humans can still pass the tests with ease. Until computers can 'imagine' what is missing from an image, robotic programs will be unable to pass these tests. The system is called IMAGINATION and you can try it out." This sounds promising given how broken current CAPTCHA technology is.

4 of 327 comments (clear)

  1. Alternative... by martin_henry · · Score: 5, Informative

    Alternative URL: http://wang.ist.psu.edu/docs/projects/imagination.html

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  2. Test site slashdotted... by thrill12 · · Score: 3, Informative

    ...but some more info here as well as a (ugh) [a href="http://wang.ist.psu.edu/imagination/imagination.ppt">powerpoint and a user study with some samples.

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  3. Re:Blind people? by Kam+Solusar · · Score: 5, Informative

    According to Wikipedia: In November 2004 article Magnitude and causes of visual impairment, the WHO estimated that in 2002 there were 161 million (about 2.6% of the world population) visually impaired people in the world, of whom 124 million (about 2%) had low vision and 37 million (about 0.6%) were blind.

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  4. Re:Blind people? by nickos · · Score: 4, Informative

    I had the same problem, and I was able to solve it in 2 steps.

    1. Strip links from messages. The spammers are trying to game Google's (and other search engine's) page ranking, and they can't do this if you don't allow them to post links. The incentive to spam your site has now gone.

    2. Insert some primitive captcha. In my case this was just a question asking the user to add 2 small numbers together. The reason this step was necessary was because despite implementing step 1, I was still getting a huge amount of automated spam from spam bots which didn't realise there was no point in spamming my site. Once a human spammer realises you've added captcha he'll come and have a look to see how easy it is to circumvent (very easy in my case). However after running a test personally he'll see there's no point and (hopefully) remove you from his list of sites to spam.

    Hope that helps anyone reading this...