Creates a boxshadow based on an image

create-boxshadow-css.js

// Create an empty canvas
var canvas = document.createElement('canvas');

// Create an image
var img = new Image();
img.src = "http://path/to/image.png";

// Wait for image to be downloaded
img.onload = function() {
	// Draw the image on the canvas
	var context = canvas.getContext("2d");
	context.drawImage(img, 0, 0);

	// Result variable
	var css = "";

	// Loop through every pixel
	for(var x=0; x < img.width; ++x) {
		for(var y=0; y < img.height; ++y) {
			// Get the colors of this specific pixel and append to css
			var colors = context.getImageData(x, y, 1, 1).data;
			css += x + "px " + y + "px rgba(" + 
					colors[0] + ", " + 
					colors[1] + ", " + 
					colors[2] + ", " + 
					Math.round((colors[3]/255)*100)/100 + 
				"),";
		}
	}
	// Replace last , with ;
	css = css.substring(0, css.length-1);

	// Do something useful
	console.log(css);
};