title: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported
body: <p>I have a canvas that was created by a user (me) dragging an image onto a dropzone. As part of saving the image, I call toDataURL. </p>
  
  <p>var theCanvas = document.getElementById ("idCardCanvas");</p>
  
  <p>var urlImage = theCanvas.toDataURL ();</p>
  
  <p>This code has worked for months when it was running from one domain, littlecardeditor.com.</p>
  
  <p>I am now in the process of adding this functionality to Radio3, at <a href="http://radio3.io/" rel="nofollow">http://radio3.io/</a>.</p>
  
  <p>Both domains are Amazon S3 buckets, both have the same CORS configuration (clutching at straws here, I don't see why CORS enters into it, since the images come off my hard disk, not from any domain).</p>
  
  <p>I dragged the images from the Desktop, based on advice from another thread here. </p>
  
  <p>None of it makes a difference. It works when I use it on littlecardeditor.com and fails with the "tainted canvas" error when called on radio3.io.</p>
  
  <p>Not sure what else to look at. Any clues would be much appreciated! :-)</p>