code: function (imgsrc, width, height, callback) {
      var args = new Args(arguments);
      checkCommonArgs(args);
  
      var Image = Canvas.Image, fs = require("fs");
      var img = new Image();
      img.onerror = function(err) {
          callback(false, err);
      };
      img.onload = function() {
          var w = img.width;
          var h = img.height;
          var newx = Math.abs(w / 2 - width / 2);
          var newy = Math.abs(h / 2 - height / 2);
          var canvas = new Canvas(width, height);
          var ctx = canvas.getContext("2d");
          ctx.drawImage(img, newx, newy, width, height, 0, 0, width, height);
          callback(true, canvas);
      };
      if (!isValidFile(imgsrc)) {
          callback(false, new Error (imgsrc + ' is not a valid file'));
      } else {
          img.src = imgsrc;
      }
  }
docs: Crops an image to bounds specified by width and height
  imgsrc - string path to image to crop
  width - integer width of cropped image
  height - integer height of cropped image
  callback - callback function(
  result - boolean true on success
  data - canvas object on success, Error on failure