viewfax displays one or more fax files in an X11 window.  The input
files may be either raw, single-page faxes received by a fax modem
with a program such as mgetty, or tiff files such as those used by
hylafax.  The first (or only) page of "PC-Research"-style (DigiFAX)
files produced by the ghostscript dfaxhigh or dfaxlow drivers can also
be displayed.

Input files using any common fax encoding such as group 3 (1 and 2
dimensional) and group 4 can be displayed.

The fax images are rendered at full resolution and then successively
scaled down by a linear factor of 2 prior to display, until they fit
on the screen.  The display can be controlled interactively using
mouse and keyboard commands.