function IsImageOk(img)
{
    // During the onload event, IE correctly identifies any images that
    // weren't downloaded as not complete. Others should too. Gecko-based
    // browsers act like NS4 in that they report this incorrectly.
    if (!img.complete)
        return false;

    // However, they do have two very useful properties: naturalWidth and
    // naturalHeight. These give the true size of the image. If it failed
    // to load, either of these should be zero.
    if (typeof img.naturalWidth != "undefined" && img.naturalWidth == 0)
        return false;

    // No other way of checking: assume it's ok.
    return true;
}