PNG merge with alpha using GD

gistfile1.php

<?php 
/** 
 * PNG ALPHA CHANNEL SUPPORT for imagecopymerge(); 
 * by Sina Salek 
 * 
 * Bugfix by Ralph Voigt (bug which causes it 
 * to work only for $src_x = $src_y = 0. 
 * Also, inverting opacity is not necessary.) 
 * 08-JAN-2011 
 * 
 **/ 
    function imagecopymerge_alpha($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $pct){ 
        // creating a cut resource 
        $cut = imagecreatetruecolor($src_w, $src_h); 

        // copying relevant section from background to the cut resource 
        imagecopy($cut, $dst_im, 0, 0, $dst_x, $dst_y, $src_w, $src_h); 
        
        // copying relevant section from watermark to the cut resource 
        imagecopy($cut, $src_im, 0, 0, $src_x, $src_y, $src_w, $src_h); 
        
        // insert cut resource to destination image 
        imagecopymerge($dst_im, $cut, $dst_x, $dst_y, 0, 0, $src_w, $src_h, $pct); 
    } 

?>