function btn_on (imgId)
{
  if (document.images)
    document.getElementById('img'+imgId).src = 'images/rooms/' + imgId + '_gr.gif';
}

function btn_off (imgId)
{
  if (document.images)
    document.getElementById('img'+imgId).src = 'images/rooms/' + imgId + '_sm.gif';
}

function showImage (imgId)
{
    if (document.images)
        document.getElementById('imgLarge').src = 'images/rooms/' + imgId + '_lg.gif';
}

function preloadRoomImage (imgId, blnIncludeLarge)
{
	if (document.images) {
		imgPreload = new Image();
		imgPreload.src = 'images/rooms/' + imgId + '_sm.gif';
		imgPreload.src = 'images/rooms/' + imgId + '_gr.gif';
		if (blnIncludeLarge) {
			imgPreload.src = 'images/rooms/' + imgId + '_lg.gif';				
		}
	}
}