title: PNG optimisation tools
body: <p>A while back I used a PNG optimisation service called (I think) "smush it". You fed it a weblink and it returned a zip of all the PNG images with their filesizes nicely, well, smushed...</p>
  
  <p>I want to implement a similar optimisation feature as part of my website's image upload process; does anyone know of a pre-existing library (PHP or Python preferably) that I can tap into for this? A brief Google has pointed me towards several command line style tools, but I'd rather not go down that route if possible.</p>