Legacy ImageMagick Discussions Archive

peixe01 wrote:thanks fred, thast just so much information i am not sure what to grab, all my tests fail, i though this would be somewhat easy, why would -draw be needed? both images have the same size. -layers composite also not sure, there is only 1 layer with transparency, the foreground image.

peixe01 wrote:one thing i notice is that the wheel loses quality when running the command via PHP, does that make any sense?


check the final result: http://www.bulletdrive.com/captcha/ver2/go.php
(refresh gives new captcha)

i save the captcha for 5 minutes and its the same for every user, then refresh it.

fmw42 wrote: Can you post your php file so that one can see the code and not just the image display?

Are you using the same version of IM with PHP as with the command line?

$possible = "112346789ABCDFGHJKLMNPQRTVWXYZ";

while (strlen(trim($captcha)) < 7) 
	{
	$char = substr($possible, mt_rand(1, strlen($possible)), 1);
	$captcha .= $char." ";
	}
	
$text = trim($captcha);

$image = "background.gif"; 
$font = "ARIALBD.TTF";
$font_size = "18";

$image_2 	= imagecreatefromgif($image);
$black 		= imagecolorallocate($image_2,0,0,0);
$white 		= imagecolorallocate($image_2, 255, 255, 255);
$grey 		= imagecolorallocate($image_2, 30, 35, 41);

$image_width = imagesx($image_2);  
$image_height = imagesy($image_2);

$text_box = imagettfbbox($font_size,$angle,$font,$text);
$text_width = $text_box[2]-$text_box[0]; // lower right corner - lower left corner
$text_height = $text_box[3]-$text_box[1];

$x = ($image_width/2) - ($text_width/2);
$y = ($image_height/2) - ($text_height/2)+8;

imagettftext($image_2,$font_size,0,$x,$y,$grey,$font,$text );

imagegif($image_2,"/home/**/public_html/captcha/ver2/text.gif");


$path = "/home/**/public_html/captcha/ver2";

$cmd = 'convert '.$path.'/wheel.gif -coalesce \-draw \'image DstOver 0,0 0,0 "'.$path.'/text.gif" \' \-layers Optimize '.$path.'/captcha.gif';

exec("$cmd 2>&1", $err); 

anthony wrote:As a catchpa it is easily defeated. Just look for the pixels that don't change much and you can remove the animated overlay!
A little morphology and the text becomes clear, ready for OCP to convert to plain text.

A animated distortion of the text as well may help so as to remove any 'static' parts to the image.

However in general animations provide far more information for the catchpa solvers to use in breaking it.
Of course it can also provide more human recognizable component too, but you need to be very very careful.

I didnt even know there could be 2 versions installed, phpinfo() doesnt say anything about IM... how would i find this out?

peixe01 wrote:

anthony wrote:As a catchpa it is easily defeated. Just look for the pixels that don't change much and you can remove the animated overlay!
A little morphology and the text becomes clear, ready for OCP to convert to plain text.

A animated distortion of the text as well may help so as to remove any 'static' parts to the image.

However in general animations provide far more information for the catchpa solvers to use in breaking it.
Of course it can also provide more human recognizable component too, but you need to be very very careful.

thanks for the input anthony, i though captcha solvers had a hard time with animated captchas humm, this is for a browser game, i dont want to piss off the players much so i am running away from those really hard captchas that even humans cant read lol

Since i posted my code above, how would you morph the text a little, do you think that alone would greatly improve its effectiveness?