ref: c57c8919e303aaad512a5e603f60d4be22d6afea
dir: /sys/src/cmd/postscript/postdmd/README/
DMD bitmap to PostScript translator. Much of the code came from abm,
which was written by Guy Riddle.
By default 6 byte patterns are used to encode the output bitmap. Use
the -b option to change the pattern size. Bitmaps are unpacked one
scanline at a time and re-encoded in a format that looks like,
bytes patterns count
where bytes and count are decimal integers and patterns is a series
of hex digits. Bytes is the number of bytes represented by the hex
pattern, and count is the number of additional times the pattern
should be repeated. For example,
2 FFFF 4
5 FFFFFFFFFF 1
10 FFFFFFFFFFFFFFFFFFFF 0
all represent 10 consecutive bytes of ones. Scanlines are terminated
by a 0 on a line by itself.