Use a CAPTCHA to prevent comment spam or to hide an email address and help digitize books at the same time

Posted on July 30, 2007 at 6:12 am

Now these days, just about every large web site has a CAPTCHA program, crazy and colorful distorted text images that appear at the bottom of registration pages or signup forms. These CAPTCHA’s are used to prevent “bots” from being able to sign up automatically since it is still impossible for computer programs to be able to read distorted text, but quite easy for the human brain to do so.

reCAPTCHA is a service where you can get CAPTCHA’s for your site that helps to digitize books. According to the site, there are over 60 million of these CAPTCHA’s that are solved ever day, resulting in about 150,000 hours of actual work being done. Their purpose is to use that time to help digitize books by having people help ”read” online.

As millions of books become digitized in the next few years (by Google, etc), they are being scanned into computers as images and then converted to text using OCR technology. The images must be converted to text so that the books can easily be searched and stored using less space than images. The issue with OCR, however, is that it’s not super accurate a lot of the time! That’s where reCAPTCHA comes in.

They send the words that cannot be read by the computers out to the Web in the form of CAPTCHA’s and let the humans decipher them. Basically, each and every word not read by the computer is made into an image and use as a CAPTCHA. The way it works is that the program generates two CAPTCHA’s, one for which it knows the answer and the other that it cannot read. When the human deciphers both and the computer see that the human correctly answered the one it already knew, it assumes that the answer to the other one is correct also. It then takes that new word that it just got the answer for and creates another pair for someone else to read to make sure the original word was correct.

There are two ways that you can use a CAPTCHA from reCAPTCHA on your site: if you run a web site or if you want to block email spam. If you’re running a blog on WordPress or Mediawiki, they have plugins that you can install without having to write any code. The email spam option is pretty nifty because it allow you to post your email address on a site, but in a short form, such as Ase…@yahoo.com and in order to reveal the full address, a user has to click on the … and solve a CAPTCHA.

The service is completely free, helps digitize books, easy to install (plugin or a few lines of HTML), and even has an audio test that can be used for people who are blind. Check it out and use it to help a good cause!

[tags]captcha, captcha image, wordpress captcha, recaptcha, captcha plugin, captcha form, using captcha[/tags]

» Filed Under Web Site Tips

Comments

5 Responses to “Use a CAPTCHA to prevent comment spam or to hide an email address and help digitize books at the same time”

Jonathan Bailey said on : July 30th, 2007 at 10:35 am

As a big reCAPTCHA fan, I’m glad to see this article, but I have to ask, why are you not using it on your comments? I’m just curious what is keeping you from it.

Thank you for discussing this!

akishore said on : July 30th, 2007 at 10:43 am

Hey Jonathan, good point! I just found out about it today and haven’t had the time yet to configure it on my blog. Hopefully, within a week or so I can get it to work with my comment form. Thanks for posting a comment! Appreciate it.

Jonathan Bailey said on : July 30th, 2007 at 11:48 am

No problem, just to let you know it’s the easiest setup I’ve done. Simply install the plugin and go!

Anitha said on : December 30th, 2007 at 1:05 am

This article is really good! still some explanation regarding the implementation of reCAPTCHA can be illustrated.

Avid said on : August 16th, 2008 at 9:30 am

Hi,
I am using
http://www.mobilefish.com/serv.....eemail.php to protect my email address against spam bots.
This site also contains other useful tools.