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Author Topic: programming:6  (Read 307 times)
zomgwtfbbq
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« on: February 20, 2010, 12:54:32 PM »
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programming:6 - captcha decode
Keeping it plain and simple, a captcha is some sort of authentication image with a text string written on it, used to prevent bot activity on eg. your website.
If you always thought captcha's are bulletproof, you were wrong, in this challenge you need to code a program that reads the string as if it were read by a human.

Sounds harder than it is, just refresh the image a couple of times, there are several important static
variables defined:

    * image-size
    * background-colour
    * foreground-colour(text)
    * font-family
    * font-size

Now that you know this, the best way to start on this challenge is by opening a stream to the captcha image and make a blueprint of the colours on the image.
To achieve this go through each pixel line by line, if you measure distances between characters, you can identify individual characters.
Good luck!
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