if(document.images)
{
  var image_array = new Array();
	
  // path to the directory with images
  var path = 'pics/bouton/';

  // enumeration of the "active" images
  image_array[0] = path + "btn_acheter_off.gif";
  image_array[1] = path + "btn_acheter_over.gif";
  image_array[2] = path + "btn_consulter_off.gif";
  image_array[3] = path + "btn_consulter_over.gif";

  var preload_image = new Array ();
 
  for(var i=0; i<image_array.length; i++)
  {
    preload_image[i]= new Image();
    preload_image[i].src = image_array[i];
  }
}