title: Why is crossorigin attribute necessary to load images into a canvas and render it?
body: <p>When loading an <code>Image</code> via setting the <code>src</code> attribute to the URL into a <code>Canvas</code> and trying to call <code>toDataURL()</code> on the canvas, this will only be allowed when the <code>crossorigin</code> attribute is set before loading the <code>Image</code>.</p>
  
  <p>Why is this though? If the image has the proper <code>Allow-Access-Control-Origin</code> header. Is it because the <code>Origin</code> attribute is not used when loading an <code>Image</code> via a URL (i.e. the <code>Origin</code> header is only included when the <code>crossorigin</code> attribute is set)?</p>