noise.js

var fs=require('fs'),
    Canvas = require('Canvas');

/**
 * algorithm impudently stolen from http://www.noisetexturegenerator.com/
 */
var generateNoise = function(width, height, opacity, density) {
    var canvas = new Canvas(width, height),
        ctx = canvas.getContext('2d');

    var x, y,
	 	r, g, b,
	    opacity = opacity,
	    density = Math.floor(density) || 1;

	for ( x = 0; x < canvas.width; x += density ) {
		for ( y = 0; y < canvas.height; y += density ) {

			number = Math.floor( Math.random() * 256 );
			ctx.fillStyle = 'rgba(' + number + ',' + number + ',' + number + ',' + opacity + ')';
			ctx.fillRect(x, y, 1, 1);

		}
	}

    return canvas.pngStream();
}

generateNoise(100, 100, 0.7, 10).pipe(fs.createWriteStream('test.png'));