blah.php

<?php
session_start();
define('CAPTCHA_NUMCHARS', 4);

$pass_phrase = "";
for($i = 0; $i < CAPTCHA_NUMCHARS; $i++) {

    $pass_phrase .= chr(rand(97, 122));

}
$_SESSION['cap_code'] = $pass_phrase;

define('CAPTCHA_WIDTH', 70); define('CAPTCHA_HEIGHT', 20);

$img = imagecreatetruecolor(CAPTCHA_WIDTH, CAPTCHA_HEIGHT);
$gc = rand(1, 1);

if($gc == '1')
{
//blue bg 30-144-255
//white text 225-225-225
$bg_color = imagecolorallocate($img, 105,105,105);
$text_color = imagecolorallocate($img, 192,192,192);
}

if($gc == '2')
{
//green bg 124-252-0
//black text 0-0-0
//red lines 255-0-0
//green dots 124-252-0
$bg_color = imagecolorallocate($img, 124, 252, 0);
$text_color = imagecolorallocate($img, 0, 0, 0);
$graphic_line_color = imagecolorallocate($img, 225, 0, 0);
$graphic_dot_color = imagecolorallocate($img, 124, 252, 0);
}

if($gc == '3')
{
//red bg 255-0-0
//blue text 30-144-255
//black lines 0-0-0
//green dots 124-252-0
$bg_color = imagecolorallocate($img, 225, 0, 0);
$text_color = imagecolorallocate($img, 30, 144, 255);
$graphic_line_color = imagecolorallocate($img, 0, 0, 0);
$graphic_dot_color = imagecolorallocate($img, 124, 252, 0);
}

if($gc == '4')
{
//yellow bg 255-255-0
//red text 255-0-0
//blue lines 30-144-255
//black dots 0-0-0
$bg_color = imagecolorallocate($img, 225, 225, 0);
$text_color = imagecolorallocate($img, 225, 0, 0);
$graphic_line_color = imagecolorallocate($img, 30, 144, 255);
$graphic_dot_color = imagecolorallocate($img, 0, 0, 0);
}

if($gc == '5')
{
//blue bg 30-144-255
//yellow text 255-255-0
//green lines 124-252-0
//red dots 255-0-0
$bg_color = imagecolorallocate($img, 30, 144, 255);
$text_color = imagecolorallocate($img, 225, 225, 0);
$graphic_line_color = imagecolorallocate($img, 124, 252, 0);
$graphic_dot_color = imagecolorallocate($img, 225, 0, 0);
}


imagefilledrectangle($img, 0, 0, CAPTCHA_WIDTH, CAPTCHA_HEIGHT, $bg_color);

for($i = 0; $i < 15; $i++) {

    imageline($img, 0, rand() % CAPTCHA_HEIGHT, CAPTCHA_WIDTH, rand() % CAPTCHA_HEIGHT, $graphic_line_color);
}

for($i = 0; $i < 150; $i++) {

    imagesetpixel($img, rand() % CAPTCHA_WIDTH, rand() % CAPTCHA_HEIGHT, $graphic_dot__color);
}

imagettftext($img, 13, 0, rand(12,22),  CAPTCHA_HEIGHT - rand(5, 10), $text_color, 'ariblk.ttf', $pass_phrase);

header('Content-type: image/png');
imagepng($img);
destroyimage($img);

?>