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Flickr Captcha

A captcha is a way to tell a computer from a real person, this is done to verify a real person to, for example, add a comment to a blog. The test is usually some kind that is hard to do in software but simple for us humans to do, a common example is reading text from an image.

Another test that is hard for computers but easy for us is image recognition - this is where flickr comes in. By selecting certain random images from flickrs huge base we can create a test that we can use to authorise a person.

It's quite a straight forward process. We just need two different sets of photos, mix them up and allow a user to choose one of the sets. In flickr we can get a selection of photos by tag name. We connect to flickr and request a number of photos with two different tags - the tags should be contained in two unassociated categories: "tiger" and "lion" would not be a good choice, but something like "banana" and "zebra", or "spaghetti" and "clouds" are better.

This program is no longer working due to a change at Flickr to encrypting all traffic, even publicly available images. I'll fix it once I have more time, so come back later... Sorry.

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