sub ImageNotDark  {
# Argument is one reference to an image object.
# ImageNotDark compares the image with a blank black canvas.  If the comparison is
# above the defined threshold, the image is bright enough to send (not dark).
# the return value is true if the images is bright enough.

    my $iutImage = Image::Magick->new;  #the image tested for darkness
    $iutImage->Read(@_);  # get the image under test (iut)