.out 
{
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)";
    filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
}

.in 
{
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(grayscale=0)";
    filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=0);
}