title: PHP - Generate transparency (or opacity) gradient using image
body: <p>Using PHP is it possible to take an existing image and produce a copy where the original image changes from 100% opaque to 0% opaque (or 0% transparent to 100% transparent!)?</p>
  
  <p>Thanks,</p>
  
  <p>Toby</p>
  
  <p><em><strong>EDIT: I realise my question was unclear, apologies. I want to take an image and create an opacity gradient across it, so the image is 100% opaque at the top, 100% transparent at the bottom and translucent in between.</em></strong></p>