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+                                      PNG8
+                                      ====
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License (Version 3) for more details.
+
+Usage:
+------
+
+png8 <options> <file>   -- convert a file
+
+
+Options
+-------
+
+General switches:
+-h         - Help text.
+
+One of these switches must be provided:
+-1         - Produce a monochrome sprite data set (e.g. Spectrum).
+-4         - Produce a 4-colour sprite data set (e.g. Commodore 64).
+
+Optional switches:
+-b         - Don't treat black the same as a transparent pixel.
+-p <text>  - Use <text> in place of 'byte' for output.
+-s         - For monochrome data, produce pre-shifted values.
+-w <width> - Set the sprite width to <width>.  This must be a multiple of 8.
+-d         - Don't use double-width pixels in 4 colour mode.
+-c0        - Set colour 0 to RGB value RRGGBB, expressed as a hex number.
+-c1        - Set colour 1 to RGB value RRGGBB, expressed as a hex number.
+-c2        - Set colour 2 to RGB value RRGGBB, expressed as a hex number.
+-c3        - Set colour 3 to RGB value RRGGBB, expressed as a hex number.
+
+Instructions
+------------
+
+PNG8 processes a sprite image strip and produces output that should be
+compatible with most 8-bit assemblers.
+
+For monochrome images it produces 1-bit per pixel output, where any pixel that
+is transparent or black (by default; this can be disabled with the -b switch)
+is treated as a clear bit in the generated output.  Other pixels are treated as
+a set bit.
+
+For 4-colour images it generates bit patterns "00" for colour 0 (default black),
+"01" for colour 1 (default red), "10" for colour 2 (default green) and "11" for
+colour 3 (default blue).
+
+The colours used can be controlled by the switches -c0 to -c3.