If you need to view a, say 640x400, picture in HAM mode, you will need to scale
it down to 320x400, as you cannot get HAM in high resolution. To do this, you
can either use fant (too slow), or something like rlezoom 1 2 | avg4 (requires
too much memory, more than I have in my 3MB Amiga).

Since I found I wanted to do this kind of scaling very often, I modified avg4.c
to produce avg2.c, which does exactly that. The context diffs are in file
DIFF_avg4_avg2.
