/*
   * Pixastic Lib - Posterize effect - v0.1.0
   * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
   * MIT License [http://www.opensource.org/licenses/mit-license.php]
   */
  
  Pixastic.Actions.posterize = {
  
          process : function(params) {
  
                  
                  var numLevels = 256;
                  if (typeof params.options.levels != "undefined")
                          numLevels = parseInt(params.options.levels,10)||1;
  
                  if (Pixastic.Client.hasCanvasImageData()) {
                          var data = Pixastic.prepareData(params);
  
                          numLevels = Math.max(2,Math.min(256,numLevels));
          
                          var numAreas = 256 / numLevels;
                          var numValues = 256 / (numLevels-1);
  
                          var rect = params.options.rect;
                          var w = rect.width;
                          var h = rect.height;
                          var w4 = w*4;
                          var y = h;
                          do {
                                  var offsetY = (y-1)*w4;
                                  var x = w;
                                  do {
                                          var offset = offsetY + (x-1)*4;
  
                                          var r = numValues * ((data[offset] / numAreas)>>0);
                                          var g = numValues * ((data[offset+1] / numAreas)>>0);
                                          var b = numValues * ((data[offset+2] / numAreas)>>0);
  
                                          if (r > 255) r = 255;
                                          if (g > 255) g = 255;
                                          if (b > 255) b = 255;
  
                                          data[offset] = r;
                                          data[offset+1] = g;
                                          data[offset+2] = b;
  
                                  } while (--x);
                          } while (--y);
                          return true;
                  }
          },
          checkSupport : function() {
                  return Pixastic.Client.hasCanvasImageData();
          }
  }