imageheight = 130;
clipwidth = 175;
imagewidth = 525;
movesize = 1;
speed = 150;

var left = 0;
var right;
var timer;
var dir = 0;

function panImage()
{
if(dir == 0)
{ if(left < imagewidth - (clipwidth + movesize))
{
left += movesize;
}
else
{
dir = 1;
}
}
else if(dir == 1)
{ if(left > movesize)
{
left -= movesize;
}
else
{
dir = 0;
}
}
right = left + clipwidth;
document.getElementById("pan").style.left = -left;
document.getElementById("pan").style.clip = "rect(0 " + right + " " + imageheight + " " + left +")";
timer = setTimeout("panImage()",speed);
}