Shadow of rotating black holes on a standard background screen
  We present the shape of the black hole shadow on the standard background
screen as it is registered by the distant observer. The screen is an infinite
plane, emitting the quanta uniformly distributed to a hemisphere. The source of
emission is considered to be optically thin and optically thick. It is shown
that the shape of a black hole shadow depends crucially on the angle between
the plane and the view line to the distant observer. The shadow shapes for the
different values of this angle are also presented. Both Schwarzschild and Kerr
metrics are considered.
