Simple php Image Captcha

Hello all,

my next work is a very simple image captcha php class which simple prints a random image with string on it which is very useful for security purposes.

the file could be downloaded from http://nasaralla.googlecode.com/files/captcha.php

and the simple to use instructions are as follows:
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//include the class file
include("captcha.php");
//instanciate the class
$c = new Captcha();
//generate the random string with this function
$c->generateCaptcha();
//print the image
$c->printCaptcha();
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