I’m sure that a lot of people have heard about Captcha…if you have downloaded files from RapidShare or tried to post comments on a blog (like mine) or register for a new site service or something like that, you have probably come across Captcha.

Captcha stands for Completely Automated Turing Test To Tell Computers and Humans Apart. It is design to prevent automated systems or bots from impersonating a human to post spam or automatically register on forums with the intent of posting spam there. With Captcha, you are essentially presented with a series of letters and number or words that may appear wavy or skewed in some way. You are then requested to “translate” what you see and type it into a field. Only if you do this correctly, can you proceed with your action. You can read all about Captcha on this Wikipedia article.

Enter reCaptcha…where if you do the action, you are actually help to digitize old text. It’s actually a very interesting concept. There are thousands of old text that are currently being digitized. However, even some of the most sophisticated OCR (Optical Character Recognition) recognizes the old text incorrectly. This is where reCaptcha has come up with a really interesting approach to solving this problem.

reCaptcha presents the user with two words, one that is known and already been “translated” from an image to a word and the second, one that has not been translated. If the user gets the first one correct, then the Captcha system assumes the second one has been entered correctly and then stores that result. I believe it continues to present the word with other “known” words until a sample of users has identified the word accurately a significant amount of time. It’s pretty ingenious. You can read more details about this technology and initiate here.

Or you can test it out and identify some old text by posting a comment below (or now on any of my blog entries). reCaptcha has plugins for WordPress, MediaWiki, phpBB, Movable Type, and Typo3 as well as the major web development environments: PHP, Ruby and Perl.

Your comments on a blog or webform can now be used to translate old text. In my opinion, this is a fantastic idea of old meeting new. So leave a comment!