function colorToHex(color)
{
  if ( color == undefined || color == null || color == '' || color == 'transparent' || color == 'Transparent' || color.substr(0, 1) == '#')
  { return color; }
  
  var digits = /(.*?)rgb\((\d+), (\d+), (\d+)\)/.exec(color);
  
  var red = parseInt(digits[2]);
  var green = parseInt(digits[3]);
  var blue = parseInt(digits[4]);
  
  var rgb = blue | (green << 8) | (red << 16);
  return digits[1] + '#' + rgb.toString(16);
}