Sylleptic

Lots of people have problems with spam, in their email, but web developers also have problems with people putting garbage into websites. I get a lot of comments from spammers who are trying to get links to their websites onto my blog. We get computer programs trying to win (by cheating) competitions we have created for our clients.

One of the solutions to that has always been the tedious email verification, login, password thing, which is too much if you just want someone to comment on your blog. Captcha is another solution, and I’ve just discovered (thanks to O’Reilly again for this) a brilliant spin on Captcha.

What is Captcha? It stands for “Completely Automated Public Turing test to tell Computers and Humans Apart” and it means putting something on screen that a robot or a piece of software can’t (easily) get past. The most common thing to do is to display an image containing some letters and numbers, and ask the user to read it and type in what it says. If you mess with the formatting enough, it becomes pretty much impossible for a piece of software to read something that’s easy for most of us people. So there are still some things we do better than computers…

reCaptcha takes that a step further. They’re using it to test and correct scans from documents, to check the scans, and to make better scanning software. They display the results of document scanning to a bunch of users, and the majority answer turns out to be the right one. A by-product of this is that it allows us to check that we have a human in front of the web page.

This must be one of those things that separates geeks from the rest, but I just love the elegance of this. Google has its image tagging game, which is slowly tagging all the pictures on the web by getting people to tag things competitively. reCaptcha is going to check lots of optical character recognition software out, while reducing the amount of spam I get on my blog.

Try it now: put a comment on the blog and see what happens.