Is there a CPAN module that distorts an image to make it only human-readable?

soon_j has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Is there a CPAN module that distorts an image to make it only human-readable? by pboin (Deacon) on Apr 19, 2005 at 12:19 UTC
You're looking for a CAPTCHA: "Completely Automated Public Turing test to tell Computers and Humans Apart". Wikipedia Entry CPAN: Authen::Captcha	[reply]
Re^2: Is there a CPAN module that distorts an image to make it only human-readable? by Mutant (Priest) on Apr 19, 2005 at 12:40 UTC
And as pointed out in Wikipedia, these sorts of tests cannot (usually) be passed by visually impaired users.	[reply]
Re: Is there a CPAN module that distorts an image to make it only human-readable? by gwhite (Friar) on Apr 19, 2005 at 12:23 UTC
GD-SecurityImage g_White	[reply]
Re: Is there a CPAN module that distorts an image to make it only human-readable? by pelagic (Priest) on Apr 19, 2005 at 12:17 UTC
You might be interested in how merlyn would have solved this problem back in 2001 if not jcwren would have hacked it a little bit later. ;-) pelagic	[reply]
Re: Is there a CPAN module that distorts an image to make it only human-readable? by b10m (Vicar) on Apr 22, 2005 at 11:59 UTC
merlyn's example can relatively been broken easilly using for instance gocr (and a little image magick) From a shell: `$ mogrify -negate <image.png> $ gocr <image.png>` [download] -- b10m All code is usually tested, but rarely trusted.	[reply] [d/l]
Re: Is there a CPAN module that distorts an image to make it only human-readable? by Joost (Canon) on Apr 19, 2005 at 12:39 UTC
Whenever I see this type of system, I'm wondering how on earth blind people (using a screen reader, or braille interface) could use it. I can understand the usefulness of the scheme, but I'm wondering if there isn't a way of testing for a "real human" that doesn't involve breaking the accessibility of the system. update: Here's a link from the above mentioned wikipedia article about this problem: http://www.w3.org/TR/turingtest/ "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re^2: Is there a CPAN module that distorts an image to make it only human-readable? by PreferredUserName (Pilgrim) on Apr 19, 2005 at 13:27 UTC
They often have an accompanying link that does some audio thing (I've never clicked it) for the benefit of vision-impaired folk, which at least decreases the pool of people it stops. I imagine flash-heavy sites are much more of a problem for the average disabled web surfer.	[reply]
Re^3: Is there a CPAN module that distorts an image to make it only human-readable? by Joost (Canon) on Apr 19, 2005 at 15:16 UTC
Flash is a problem for many reasons, but if your audience has the flash player installed, it can be used to create an accessible interface (with keyboard commands, alternatives for images etc). At least, that's what I've been told by some people who spend a lot of time creating websites for an institute for the blind. I haven't really been interested in flash enough to try it myself, though. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re^2: Is there a CPAN module that distorts an image to make it only human-readable? by BrowserUk (Patriarch) on Apr 19, 2005 at 14:01 UTC
Just a thought, but for a blind person to be using the internet, they usually have some kind of speech reader, so couldn't the be an alternative that sends them .wav file which they listen to and retype? It should be possible to make the .wav files sufficiently different each time that it would be pretty akward to automate the response. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. Rule 1 has a caveat! -- Who broke the cabal?	[reply]
Re^3: Is there a CPAN module that distorts an image to make it only human-readable? by Joost (Canon) on Apr 19, 2005 at 15:11 UTC
I think quite a lot of blind people actually use a braille reader, so counting on audio isn't foolproof, though I guess most will have audio anyway - unless they also have hearing problems. However, creating audio checks is hard, apparently: (From the CNET article referenced in the w3c article mentioned above): Microsoft's Hotmail service provides an audio alternative to its visual test, in which letters are read aloud instead of being displayed in a graphical file. But one such audio file--deliberately garbled to prevent its being read by a computer--was unintelligible to four out of four CNET News.com reporters, all with good hearing, who tried to decipher it. It's better than no alternative, ofcourse. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re^4: Is there a CPAN module that distorts an image to make it only human-readable? by Anonymous Monk on Apr 19, 2005 at 16:12 UTC
Re^4: Is there a CPAN module that distorts an image to make it only human-readable? by jhourcle (Prior) on Apr 19, 2005 at 15:43 UTC
Re^5: Is there a CPAN module that distorts an image to make it only human-readable? by Anonymous Monk on Apr 19, 2005 at 16:15 UTC
Re^2: Is there a CPAN module that distorts an image to make it only human-readable? by Anonymous Monk on Apr 20, 2005 at 01:25 UTC
Wow... I wasn't expecting tons of response... but I really appreciate all of them. Unfortunately, as of the moment my web application is not geared for the visually impaired. It is only designed for a small audience that allows them to take exams via the web. Simply saying... my online exams wouldn't also work for the visually-impaired. However what was brought up here is a situation that I never thought of... honestly. I find this to be a very valuable suggestion... and I'll do what I can to include this capability in the future.	[reply]
Re^3: Is there a CPAN module that distorts an image to make it only human-readable? by Anonymous Monk on Apr 20, 2005 at 09:16 UTC
Simply saying... my online exams wouldn't also work for the visually-impaired. Says who? Visually-impaired doesn't imply totally blind. People can have all kinds of restricted vision disorders. Some may be unable to take your exam - but some may be able. But using a distorted image as firewall can be a hurdle too high to take for some people able to take your exam. OTOH, if it's just a site that's about online exams which can't be taken by visually impaired, why the distorted image in the first place? Afraid the bots might take the exams?	[reply]
Re: Is there a CPAN module that distorts an image to make it only human-readable? by zentara (Cardinal) on Apr 19, 2005 at 13:28 UTC
I have an idea (again :-) ). Why not create an audio link to keep accessibility for blind users? You could create your image, say a number, and distort it. Then concurrently, take the number, and feed it to flite . Then make an adjacent "accessibility link" which would play the wav, au, or mp3 of the number? I'm not really a human, but I play one on earth. flash japh	[reply]
Re: Is there a CPAN module that distorts an image to make it only human-readable? by b10m (Vicar) on Apr 19, 2005 at 13:59 UTC
Why not skip all of these horribly annoying ideas? If some spammer/evildoer really wants to get your site bad, (s)he can hire some idiots who will fill out a form. Please, oh please stop the madness... -- b10m All code is usually tested, but rarely trusted.	[reply]
Re^2: Is there a CPAN module that distorts an image to make it only human-readable? by Anonymous Monk on Apr 19, 2005 at 16:18 UTC
Hire an idiot? Not needed. Just setup your own site ("free pr0n") that requires "visual identification", and show your new users the images that you've copied from the site you want to have access to. Easily automated.	[reply]
Re^3: Is there a CPAN module that distorts an image to make it only human-readable? by Joost (Canon) on Apr 19, 2005 at 16:54 UTC
Re^3: Is there a CPAN module that distorts an image to make it only human-readable? by steelrose (Scribe) on Apr 19, 2005 at 18:31 UTC
Re: Is there a CPAN module that distorts an image to make it only human-readable? by fraterm (Scribe) on Apr 19, 2005 at 18:27 UTC
Aside from the usability concerns for people with differing sensory delivery needs, the perl modules in the ImageMagick package may be able to perform such effects on things in an efficient way. The specific perl tools are located here. All of the discussion on audio format implementations of CAPTCHA are interesting but not so nice on a braille reader. To this I propose live chat operator conversation as a potential alternative, but I'm sure some method of exploiting this using IRC/IM bot techniques may confuse anyone set in as a further alternative to verify the humanity of the querent. Squibbie Pooh Ski Doo.	[reply]
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