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

by soon_j (Scribe)
on Apr 19, 2005 at 12:08 UTC ( #449204=perlquestion: print w/ replies, xml ) Need Help??
soon_j has asked for the wisdom of the Perl Monks concerning the following question:

I have been searching for quite some time for a CPAN module that allows you to distort an image and make it human-readable only... like what they do in Yahoo or hotmail when you sign-up for a new account. I wanted to avoid automated registrations so I need to do something like this... but I can't seem to find it now.

Comment on Is there a CPAN module that distorts an image to make it only human-readable?
Re: Is there a CPAN module that distorts an image to make it only human-readable?
by pelagic (Curate) on Apr 19, 2005 at 12:17 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>
      --
      b10m

      All code is usually tested, but rarely trusted.
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
      And as pointed out in Wikipedia, these sorts of tests cannot (usually) be passed by visually impaired users.
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
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
      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.

        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.

      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?
        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.

      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.
        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?

Re: Is there a CPAN module that distorts an image to make it only human-readable?
by zentara (Archbishop) 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

      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.
        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.

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.
Re: Is there a CPAN module that distorts an image to make it only human-readable?
by TedPride (Priest) on Apr 22, 2005 at 10:30 UTC
    It's highly unlikely that a blind person with access to a computer is not going to have access to at least one person with sight. This is a non-issue, imho.
      It's highly unlikely that a blind person with access to a computer is not going to have access to at least one person with sight.

      Why on earth would you think this would be true? Blind people have lives you know - live by themselves - don't want to have phone a friend to logon to a site.

      This is a non-issue, imho.

      This is completely untrue. It is an issue. It's an issue with people I know. It's actually an issue with people with good sight since the evolutionary war between the image readers and the image distorters has caused the images to be difficult for people without disabilities to read.

      Really? A lot of blind people live either alone, or with a blind spouse. And even if they are married, or living together with a sighted person, that person isn't always around. People have jobs for instance. (Yes, blind people too!) Furthermore, people (not just blind people) hate to be dependent on other people for doing things that ought to be simple.

      I agree with you that "blind people can't use it" shouldn't be the number one argument against CAPTCHAs. Although I do believe there are quite a lot of blind people using the net with a lot of joy, there might be a lot of sites that are blind-people-unfriendly to begin with (photo sites, for instance). These could use CAPTCHAs with probably no problem for they probably don't lose customers.

      The number one reason not to use CAPTCHAs should be because it's annoying to everyone. I've seen sites with blind-friendly approaches (like: What comes after: one, two, three, ...). Blind people can fill them out, yet these approaches are also annoying (at least to me).

      It also seems the trend to make your images as hard to readparse as possible, resulting in images that are really hard to read, even for people with perfect sight.

      Conclusion: do not use these things. Some people just are blind, like to use lynx/links, find pleasure in WWW::Mechanize, or just don't like to be challenged. Let them be.

      --
      b10m

      All code is usually tested, but rarely trusted.

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