Digitizing Books One Word at a Time.

Now that I've written about CAPTCHA (read it here), let me tell you something about reCAPTCHA.

reCAPTCHA is a free CAPTCHA service that helps to digitize books. Millions of CAPTCHAs are solved by humans around the world every day. In each case, roughly ten seconds of human time are being spent. reCAPTCHA channels the effort spent solving CAPTCHAs online into "reading" books.

Using Optical Character Recognition, the photographically scanned book pages are transformed into text. The problem is that OCR is not perfect.

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. 

Here is the tricky part. If a computer can't read such a CAPTCHA, how does the system know the correct answer to the puzzle? Here’s how: They give two words instead of one – one which cannot be read correctly by OCR and the next 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. 

What if we can read only one of them? Say, something like this.

I enter the word ‘(Humphrey’ correctly but not the next. In this case, it will be still considered correct but it would not take it for granted. The system then gives the new image to a number of other people to determine, with higher confidence, whether the original answer was correct.

Ref: reCAPTCHA / WIKI

CAPTCHA

Pain in the ass!

Yes, that’s the first thing that comes to my mind when I come across a CAPTCHA. Until recently, I was completely against CAPTCHA. Maybe because I found it really difficult to identify the words or letters or numbers.

Have you ever thought why did they even bring this concept? I hadn’t too, until yesterday when my friend gave me a short (but wonderful) lecture on CAPTCHA. I always thought CAPTCHA is a word, similar to ‘WHATCHA’. CAPTCHA is the acronym for Completely Automated Public Turing test to tell Computers and Humans Apart.

Consider the ‘Comments’ section on your blog. There are two ‘fields’ there. One is a text box where you can enter your ‘comment’ and another is a ‘Publish’ button. There are only two steps involved in this process. 1. Enter comments in the textbox. 2. Hit ‘Publish’. It’s child’s play for a computer freak to program these. I mean, to open your blog, select ‘comments’ link, enter some text and hit submit. Think of it if he runs this loop a million times? A million comments for your blog. Wow! That’s something good, isn’t it? ;)

Okay. Think if he is doing this on an email registration page. A million user ID’s and passwords with no one actually using it. They can do this with any permutation and combination of alphabets and numbers ranging different lengths. So when you try to create a user id or any user id, all you see is ‘user id already exists’.

CAPTCHAs are designed to be easy for a computer to generate, but difficult for a computer to solve, so that if a correct solution is received, it can be presumed to have been entered by a human. CAPTCHAs have many applications for security which includes – preventing comment spams in blogs, protecting website registrations, online polls, and most importantly, to prevent dictionary attacks*.

So, when an automated program or a ‘bot’ tries to gain access, CAPTCHA GOTCHA!

Ref: CAPTCHA / WIKIPEDIA 

*CAPTCHAs can also be used to prevent dictionary attacks in password systems. The idea is simple: prevent a computer from being able to iterate through the entire space of passwords by requiring it to solve a CAPTCHA after a certain number of unsuccessful logins.

PS: I found the topic interesting. Thought I will write about it here. Hope its informative.

use all your fingers.

I started to developing the interest of typing-without-looking-at-the-keyboard. It has always been a mystery for me when I see someone typing so fast hovering their fingers over the keyboard. And I found out how ;) khe khe khe... Secret is to 'Learn Typing'! So, for those who are interested, please do not waste your time downloading some stupid software.

Check this out - http://www.typingweb.com/

I hope it helps! Happy typing!

Photo Credit: Benjamin Earwicker / Image / Website