August 09, 2007

Few irritating captcha's - Image verification

"Oh God! Its irritating. Am trying to finish this form, but this image-verification is killing my time and patience. "

This is not from my mouth. This is what I have seen some user say while filling forms in few websites. The worst part is they don't understand the characters in image. Some time its so tough that they don't understand 50% of the characters. We all know that Captcha helps preventing the softwares from autofill.

Another user says
"I tried to change the captcha and whole data is lost. Again i have to re enter the data. Then once again captcha is not clear & I clicked 'show different image' and whole page refreshed and all the datas I entered was lost and I never filled the form in that website & all my friends faced the same issue."


"CAPTCHA" is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart", trademarked by Carnegie Mellon University. - Wikipedia

Yes - we all have experienced some way of other with different types captcha used in web. Below are some Good and Bad example of captcha.

Good Captchas - easy to understand for users

This captcha is pretty straight forward. User need no second thought.
good captcha - easy for user to fill the word

Look at this recaptcha, its so simple and user has option to listen to audio on worst case.

good captcha - easy for user to fill the word

Pretty straight forward
good captcha - easy for user to fill the word

Its simple & no issues in understanding the text from image.
good captcha - easy for user to fill the word

Next two is from msn. Some images are difficult to understand, but its rare. Its also accessible for users with disabled. Even normal users can user the audio to enter the information
good captcha - easy for user to fill the word

Another screen shot from msn.
good captcha - easy for user to fill the word

This is from Google. Very-very easy to understand and also easy for visually challenged.
good captcha - easy for user to fill the word


Bad Captcha - by which user gets irritated and big loss for business

Oops - Captcha with encryption. its time consuming and prone to mistakes. And its not accessible & easy to use for visually challenged.
bad captcha - gives opportunity for user to make mistakes

Below image is readable, but not accessible. No audio facility.
bad captcha - gives opportunity for user to make mistakes

Oops - one of the worst.
bad captcha - gives opportunity for user to make mistakes

Ooops - not again, this captcha is bad.
bad captcha - gives opportunity for user to make mistakes

facebooks captcha- few characters are difficult to understand. Below one is easy though.
bad captcha - gives opportunity for user to make mistakes

9 comments:

Anonymous said...

i always had problem in understanding this blogger's image verification. Well !!! I think the services should use simple math tricks or some other logical questions for verification.Nice article.

gg. said...

Good point! Captcha's are becoming very popular these days. I myself have had frustrations while filling some of the forms, but some of them are pretty straightforward as shown in few examples here. Nice article as well as examples.

Alok Jain said...

Hey Rajesh,

Good collection .. I have two questions:

1. Wha are alternative solutions towards the problem CAPTCHA is trying to solve

2. What are good practices for this kind of implementation of CAPTCHAs

Rajesh Anandakrishnan said...

Kanak, Yes you are right. There are some sites using simple math tricks like 2 + 4 = ? Simple images - Captcha, can always replace the the math trick.

Rajesh Anandakrishnan said...

Hi Alok, you always trigger the thoughts & Once again.

For 1st question - I have not seen much of techniques available to replace captcha. One of the technique is simple math trick. But simple programming can hack the math trick. Another method can be like this: "what is the 7th character from e in reverse order" - oops, its going to be like a puzzle.

I thought of another method while replying this comment - showing pictures and asking to choose from the choices of words. Let me think of few more options will write on this Alok.

2 Question: I have mentioned the advantages and disadvantages of each captcha in blog. To be more specific, I will consolidate and update in a blog with best practices. Thanks for the thought. and give your reply for this too.

Rajesh Anandakrishnan said...

Geethi, you are right. Check this blog: www.kunalnanda.com. Its a wonderful blog on Cricket. I want to comment appreciating this blog. But look at the captcha. I tried 5 times and I failed and so he missed out few comment from me.

Anonymous said...

As for alternatives: I tried javascript in another website. Guess what - a robot came through. Stunning. This robot must have been a browser - maybe an infected explorer running as a backgroundprocess or something.

So .. javascript is not an alternative.

$2c,
*-pike

Anonymous said...

In 99% of the forms though, the question is not wether your site is *eventually* hackable by a robot, but wether it is sensitive for massbrowsing spamrobots. I assume something simple like "retype the word GEEZER in the box below" will already save you from a lot of trouble - even without distorting that word.

There is no need to use more irritating CAPTCHAs unless there actually is a security risk, imho ...

*-pike

Anonymous said...

Until alternatives are offered (audio, alt text etc.) then CAPTCHAs are an inaccessible way of protecting against bots. What's worse is that some big companies like Myspace and Facebook (to name a few) are IGNORING emails from blind and partially sighted users who are asking for alternatives. That's really bad.