<?php 
$check=rand(1000,9999);

Session_start(); 

$_SESSION["check"] = $check; 

$img = imagecreate(80,30); 

imagefill($img,0,0,ImageColorAllocate($img,255,255,255)); 

$y1=rand(0,30); 

$y2=rand(0,30); 

$y3=rand(0,30); 

$y4=rand(0,30); 

imageline($img,0,$y1,70, $y3,ImageColorAllocate($img,55,255,25)); 

imageline($img,0,$y2,70, $y4,ImageColorAllocate($img,55,55,255)); 

$strx=rand(3,15); 

$stry=rand(2,15); 

imagestring($img,5,$strx,$stry,substr($check,0,1),ImageColorAllocate($img,34,87,100)); 

$strx+=rand(15,20);

$stry=rand(2,15); 

imagestring($img,5,$strx,$stry,substr($check,1,1),ImageColorAllocate($img,781,117,78)); 

$strx+=rand(15,20);

$stry=rand(2,15); 

imagestring($img,5,$strx,$stry,substr($check,2,1),ImageColorAllocate($img,160,40,40)); 

$strx+=rand(15,20);

$stry=rand(2,15); 

imagestring($img,5,$strx,$stry,substr($check,3,1),ImageColorAllocate($img,25,55,10)); 

Header("Content-type: image/PNG"); 

ImagePNG($img);