A better captcha. - PHP Code Bank

                <?php

/* Made by TheMasterSinner */

// start session
session_start();

// make image
$image = imagecreate(66, 26);

// define some colors
$white  = imagecolorallocate($image, 255, 255, 255);
$black  = imagecolorallocate($image, 0, 0, 0);

// set the background color to white
imagefill($image, 0, 0, $white);




/**************************************************
put some colored squares in the background
**************************************************/

// draw horizontal lines
for ($i=0; $i<=65; $i+=5) {
	imageline($image, $i, 0, $i, 26,  $black);
}

// draw vertical lines
for ($i=0; $i<=25; $i+=5) {
	imageline($image, 0, $i, 66, $i,  $black);
}

// fill in the squares with random colors
for ($x=3; $x<=25; $x+=5) {
	for ($i=3; $i<=65; $i+=5) {
		// make a random color
		$rndColor = imagecolorallocate($image, rand(100, 150), rand(100, 150), rand(100, 150));
		
		// fill in the square with the random color
		imagefill($image, $i, $x, $rndColor);
	}
}




/**************************************************
write a random string on the image
**************************************************/

//make a random string
$chars  = str_shuffle('ABCDEHJMNX23456789');
$rndstr = substr($chars, 0, 6);

// set the session to the random string
$_SESSION['captcha'] = $rndstr;

// the string length
$strLen = strlen($rndstr);

// for each letter
for ($i=0; $i<$strLen; $i++) {
	// make a random color
	$rndColor = imagecolorallocate($image, rand(200, 240), rand(200, 240), rand(200, 240));
	
	// put a letter on the image
	imagestring($image, 5, (($i * 10) + 5), rand(0, 10), $rndstr{$i}, $rndColor);
}




// change the content type to a png image
header('Content-type: image/png');

// echo the image
imagepng($image);

// finished, so destroy the image
imagedestroy($image);
?>