pbmtoascii - convert a portable bitmap into ASCII graphics
Reads a portable bitmap as input.
Produces a somewhat crude ASCII graphic as output.
Note that there is no asciitopbm tool - this transformation is one-way.
flags give you two alternate ways for the bits to get mapped to characters.
the default, each character represents a group of 1 bit across by 2 bits down.
each character represents 2 bits across by 4 bits down.
With the 1x2 mode you can see the individual bits, so it's useful for
previewing small bitmaps on a non-graphics terminal.
The 2x4 mode lets you display larger bitmaps on a standard 80-column display,
but it obscures bit-level details.
2x4 mode is also good for displaying
graymaps - "pnmscale -width 158 | pgmnorm | pgmtopbm -thresh"
should give good results.
Copyright (C) 1988, 1992 by Jef Poskanzer.