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reCAPTCHA Prevent Spam and Help Digitize Books

Posted · Category: License Free, Security

A CAPTCHA is a program that can tell whether its user is a human or a computer. You’ve probably seen them — colorful images with distorted text at the bottom of Web registration forms. CAPTCHAs are used by many websites to prevent abuse from “bots,” or automated programs usually written to generate spam.

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.

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. By using reCAPTCHA, you can protect your site from abuse and help digitize books at the same time.

captcha.png

Requirements: No Requirements
Demo: http://recaptcha.net/
License: License Free

2 Comments
  • http://www.webdesignbeach.com Ognjen Knaus

    Hi,

    here’s a nice captcha we’ve done:
    http://www.webdesignbeach.com/beachbar/ajax-fancy-captcha-jquery-plugin#more-12

    More skins are there to come.
    It’s using AJAX so you don’t need flash installed in your browser.

  • http://zeleze.com dan

    funny, using reCaptcha technique you can teach computers to decipher captchas… this will take the point out of captcha.

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