Retina images quality simulator

retina.js

/**
 * Simulates how normal low-res images look on retina display
 *
 * It resamples all images (within <img> tags) to a lower resolution.
 *  We should use half the resolution of original image to be precise (because retina has 2x the density of pixels),
 *  but that doesn't show * perceived* effect. It's enough to scale by 1.75.
 *
 * Also, it would be good to resample also images used in CSS background, but I dunno how to do it :/
 *
 * Requires jQuery
 */
scale = 1.75

c = this.document.createElement("canvas")
ctx = c.getContext('2d')

$('img').each(function() {
	var i = this;

	c.width = i.width / scale
	c.height = i.height / scale

	ctx.drawImage(i, 0, 0, i.width, i.height, 0, 0, c.width, c.height)
	i.src = c.toDataURL('image/png')
});

Error: The operation is insecure. [Break On This Error]

i.src = c.toDataURL('image/png')

// any ideas? FF 16.0.1