Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
I think that's jolly inventive, even if it's not entirely practical. Of course plain ascii art is a similar tactic.

Interestingly I looked at the complementary problem last year for a rabble of grubby greyhat dotcommers in the next office to me - you guessed it, OCR for noisy .gifs (they actually did perfectly legitimate deeplinking searches ).

I used Image::Magik to read, normalise, greyscale, blur and threshold the image, then take the highest weighted sum of the AND with a test image, read nasty brute force OCR.

Eventully they replaced my code with a far faster C++ implementation that finds minimum distances between FFTs of the images, which quite frankly laughs at Perl (speedwise).

However they still get plenty of problems last time I heard. That is to say, done properly, obfuscated images can be computationally VERY hard to OCR, but it can be done.

Regardless of methodolgy there is a deeper principle at play here, which connects with what Merlyn has to say... eventually you are going to make life so difficult for your end user that any perceptual impairment they have will make reading almost impossible. My (dyslexic) Sister has a damn hard time reading those obfuscated .gifs

My hypothesis then, if you are prepared to throw enough cycles at the problem, with a good enough algorithm, the machine will always be able to filter the info from a noisy image _better_ than a human can. Hence the general method is flawed if its sole objective is to defeat bots.

A better method is to rely on questions from current events news. Make it multiple choice, and make it so that 3 wrong answers out of 5 blocks the IP for an hour.

Even something like

Which dictator has no moustache?
1 Adolf Hitler
2) Augustus Pinochet
3) Saddam Hussain
4) Josef Stalin
5) George W Bush
6) George Palpadopoulos
7) Francois "Papa Doc" Duvalier


would fool pretty much any AI :) Andy

In reply to Re: Another way to get around automated bots by andyf
in thread Another way to get around automated bots by AssFace

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others chilling in the Monastery: (3)
As of 2021-08-02 00:26 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    My primary motivation for participating at PerlMonks is: (Choices in context)








    Results (16 votes). Check out past polls.

    Notices?