have different maxvals.  The output image has the more general of the
two input formats and a maxval that is the least common multiple the
two maxvals (or the maximum maxval allowable by the format, if the LCM
is more than that).

<A NAME="lbAE">&nbsp;</A>
<H2>OPTIONS</H2>

<DL COMPACT>
<DT><B>-align=</b><i>alignment</i>
<DD>
This option selects the basic horizontal position of the overlay image
with respect to the underlying image, in syntax reminiscent of HTML.
<b>left</b> means flush left, <b>center</b> 