function imgswap(img,newsrc)
{
img.oldsrc=img.src;
img.src=newsrc;
}
function imgback(img)
{
img.src=img.oldsrc;
}

function cswap(centerimage)
{
center.src=centerimage;
}

function imgswap2(img,newsrc, centerimage)
{
img.oldsrc=img.src;
img.src=newsrc;
cswap(centerimage);
}
function imgback2(img)
{
img.src=img.oldsrc;
center.src='media/square.gif';
}