title: png compression in opencart not working
body: <p>I've been searching and trying to figure out why I can't get png image compression to work for an opencart 1.5 site I'm working on. </p>
  
  <p>On line 46 of library/image.php I modified the imagepng function to use compression 9 instead of the default 0 and it had no affect on my images. I deleted the images from the fileserver and they just repopulate with the exact same file size/quality.</p>
  
  <p>Anyone know how I can get the file sizes of my images down? A 1000x750px image is over 2M and it's killing my load times.</p>
  
  <p>Thank!</p>