createNoiseFromColors.js

function rand(min,max,round) {
  if(round === false){
    return (Math.random() * (max-min)) + min;
  }
  else {
    return Math.round((Math.random() * (max-min)) + min);
  }
}

function createNoiseFromColors(w, h){
  var canvasElement = document.createElement("canvas");
  canvasElement.id = "canvas" + rand(100000,999999);
  document.body.appendChild(canvasElement);
  var c = document.getElementById(canvasElement.id);
  var ctx = c.getContext("2d");
  c.width = w;
  c.height = h;
  var colors = [];
  for (var argIndex = 2; argIndex < arguments.length; argIndex++){
    colors.push(arguments[argIndex]);
  }
  for (var colorIndex = 0; colorIndex < colors.length; colorIndex++){
    switch (colors[colorIndex]){
      case "black":
        colors[colorIndex] = [0,0,0];
        break;
      case "white":
        colors[colorIndex] = [255,255,255];
        break;
      case "red":
        colors[colorIndex] = [255,0,0];
        break;
      case "green":
        colors[colorIndex] = [0,255,0];
        break;
      case "blue":
        colors[colorIndex] = [0,0,255];
        break;
      case "yellow":
        colors[colorIndex] = [255,255,0];
        break;
      case "magenta":
      case "purple":
      case "pink":
        colors[colorIndex] = [255,0,255];
        break;
      case "cyan":
        colors[colorIndex] = [0,255,255];
        break;
      default:
        colors[colorIndex] = colors[colorIndex].replace(/[^a-fA-F0-9]/,"");
        var hexValues = colors[colorIndex].match(/.{2}/g);
        var decValues = [];
        for (var hexIndex = 0; hexIndex < hexValues.length; hexIndex++){
          decValues.push(parseInt(hexValues[hexIndex],16));
        }
        colors[colorIndex] = decValues;
    }
  }
  ctx.fillStyle = "white";
  ctx.fillRect(0,0,c.width,c.height);
  var imagething = ctx.getImageData(0,0,c.width,c.height);
  var data = imagething.data;
  for (var i = 0; i < (data.length * 4); i++){
    var randomIndex = rand(0,colors.length-1);
    data[(i*4)+0] = colors[randomIndex][0];
    data[(i*4)+1] = colors[randomIndex][1];
    data[(i*4)+2] = colors[randomIndex][2];
  }
  ctx.putImageData(imagething, 0, 0);
}