Hi all!
For all of you that want to preserve the transparency of images, I added this function:
Code:
function setTransparency($new,$temp) 
  
    { 
        
            $transparencyIndex = imagecolortransparent($temp); 
            $transparencyColor = array('red' => 255, 'green' => 255, 'blue' => 255); 
             
            if ($transparencyIndex >= 0) { 
                $transparencyColor    = imagecolorsforindex($temp, $transparencyIndex);    
            } 
            
            $transparencyIndex    = imagecolorallocate($new, $transparencyColor['red'], $transparencyColor['green'], $transparencyColor['blue']); 
            imagefill($new, 0, 0, $transparencyIndex); 
             imagecolortransparent($new, $transparencyIndex); 
        
    }
You can call it with setTransparency($new,$temp);
just before imagecopyresampled($new, $temp, 0, 0, 0, 0, $dst_w, $dst_h, $org_w, $org_h);



Thank you very much to Boudewijn for this fantastic mod. For next reviews, it must have a direct link at the product edit screen. anybody?