function colorpic(pic_name, picnum){
	var picnum = parseInt(picnum);
	var nom = "";
	var i = 1;
	
	for(i=1; i<=picnum; i++){

		this.document.getElementById("pic"+i).style.backgroundColor = '#555555';
	}
	
	this.document.getElementById(pic_name).style.backgroundColor = '#000000';
}

function changeImage(img, pic_name, picnum){
  document.imagen.src = img;
  colorpic(pic_name, picnum);
}