of the light source to the left of the
image.  Larger settings of <B>xoffset</B> displace the shadow to the
right, as would be cast by a light further to the left.  If not
specified, the horizontal offset is half of <I>blur_size </I> (above),
to the left.

<DT><B>-y</B><I> yoffset</I>

<DD> Specifies the displacement of the light source above the top of
the image.  Larger settings displace the shadow downward,
corresponding to moving the light further above the top of the image.
If you don't specify <B>-y</