Embed external images for use in HTML canvas?

Question

I'm using JavaScript to load an image into my Canvas element in Firefox. This works fine for local images, but throws a security exception for external images. Is there any way to avoid this security exception, one that does not involve my server having to act as proxy to load the image locally (because that would stress my server)?

PS: The current code is similar to this:

var img = new Image();
var contextSource = canvasSource.getContext('2d');
contextSource.drawImage(img, 0, 0);
// get image data to do stuff with pixels
var imageDataSource = contextSource.getImageData(0, 0, width - 1, height - 1);

Answer 1

I don't think this is possible, because this could open the browser to cross domain attacks.