function ShowImg(n, x, y) {
  var contentsWindow;
  
  if (x > 800) {
    tx = 800;
    tkx = x / tx;
    x = tx;
    y = y / tkx;
  }
  if (y > 600) {
    ty = 600;
    tky = y / ty;
    y = ty;
    x = x / tky;
  }
  
  contentsWindow = window.open("/img.php?src="+n, "contents", "width="+x+"; height="+y+"; left=100; top=50; scrollbars=no");
}