We've been (re)captcha'd!

Posted By: cody

Last Updated: Wednesday July 16, 2008

After recieving numerous spam e-mails to our various departments we decided to look into where they were coming from - and as predicted it was from our contact form(s). Being the silly littls nits that we are we didn’t protect it with any sort of captcha.

I recalled Tony mentioning a few weeks ago for me to code one to add onto the forms - but being the good employee that I am I procrastinated until it was to the point of necessity. I opted to try out reCaptcha - a free service that allows you to easily implement captcha’s into your websites .. but it has a dual purpose. Essentially it allows people to help digitize books that OCR has issues reading (below is a chunk quoted from the reCaptcha site):

About 60 million CAPTCHAs are solved by humans around the world every day. In each case, roughly ten seconds of human time are being spent. Individually, that’s not a lot of time, but in aggregate these little puzzles consume more than 150,000 hours of work each day. What if we could make positive use of this human effort? reCAPTCHA does exactly that by channeling the effort spent solving CAPTCHAs online into “reading” books.

To archive human knowledge and to make information more accessible to the world, multiple projects are currently digitizing physical books that were written before the computer age. The book pages are being photographically scanned, and then transformed into text using “Optical Character Recognition” (OCR). The transformation into text is useful because scanning a book produces images, which are difficult to store on small devices, expensive to download, and cannot be searched. The problem is that OCR is not perfect.

Example of OCR errors

reCAPTCHA improves the process of digitizing books by sending words that cannot be read by computers to the Web in the form of CAPTCHAs for humans to decipher. More specifically, each word that cannot be read correctly by OCR is placed on an image and used as a CAPTCHA. This is possible because most OCR programs alert you when a word cannot be read correctly.

But if a computer can’t read such a CAPTCHA, how does the system know the correct answer to the puzzle? Here’s how: Each new word that cannot be read correctly by OCR is given to a user in conjunction with another word for which the answer is already known. The user is then asked to read both words. If they solve the one for which the answer is known, the system assumes their answer is correct for the new one. The system then gives the new image to a number of other people to determine, with higher confidence, whether the original answer was correct.

So essentially - theres so many captcha’s in use today why not make them useful and work towards something (and making employee’s lives easier while keeping bosses happy, but that’s hush hush).

I’m proud to say HawkHost is helping people read books on their computers. Amen.

Until next time!

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