(function($){
	// This function adds noise to the background-image attribute of a given element
	$.fn.noisy = function(options) {
		options = $.extend({}, $.fn.noisy.defaults, options);
		var uri, cachedUri;

		if (JSON && localStorage.getItem) {
			cachedUri = localStorage.getItem(JSON.stringify(options));
		}

		// Use localStorage cache if these options have been used before
		if (cachedUri) {
			uri = cachedUri;
		}
		else {
			var canvas = document.createElement('canvas');

			// Use fallback image if canvas isn't supported
			if (!canvas.getContext) {
				uri = options.fallback;
			}
			else {
				canvas.width = canvas.height = options.size;

				var ctx = canvas.getContext('2d'),
				    imgData = ctx.createImageData(canvas.width, canvas.height),
				    numPixels = options.intensity * Math.pow(options.size, 2),
				    maxAlpha = 255 * options.opacity;

				// Add color to random pixels in the canvas
				while (numPixels--) { // Read about the double bitwise NOT trick here: goo.gl/6DPpt
					var x = ~~(Math.random()*canvas.width),
					    y = ~~(Math.random()*canvas.height),
					    index = (x + y * imgData.width) * 4;

					var colorChannel = numPixels % 255; // This will look random enough
					imgData.data[index  ] = colorChannel;                                               // red
					imgData.data[index+1] = options.monochrome ? colorChannel : ~~(Math.random()*255);  // green
					imgData.data[index+2] = options.monochrome ? colorChannel : ~~(Math.random()*255);  // blue
					imgData.data[index+3] = ~~(Math.random()*maxAlpha);                                 // alpha
				}

				ctx.putImageData(imgData, 0, 0);
				uri = canvas.toDataURL('image/png');

				// In IE < 9 Data URI's are only displayed if they are < 32KB
				// Though IE < 9 doesn't officially support the canvas element, 
				//   certain scripts like excanvas.js will enable it and if the URI is > 32KB it won't be displayed
				if (uri.indexOf('data:image/png') != 0 || // toDataURL doesn't return anything in Android 2.2
				    $.browser.msie && 
				    $.browser.version.substr(0,1) < 9 && 
				    uri.length > 32768) {
					uri = options.fallback;
				}
			}

			if (JSON && localStorage) {
				localStorage.setItem(JSON.stringify(options), uri);
			}
		}

		return this.each(function() {
	 		$(this).css('background-image', "url('" + uri + "')," + $(this).css('background-image'));
		});
	};
	$.fn.noisy.defaults = {
		// How many percent of the image that is filled with noise, 
		//   represented by a number between 0 and 1 inclusive
		intensity:          0.9,

		// The width and height of the image in pixels
		size:               200,

		// The maximum noise particle opacity,
		//   represented by a number between 0 and 1 inclusive
		opacity:            0.08,

		// A string linking to the image used if there's no canvas support
		fallback:           '',

		// Specifies wheter the particles are grayscale or colorful
		monochrome:         false
	};
})(jQuery);