pgmtopbm(1)                                           pgmtopbm(1)


NAME
       pgmtopbm  -  convert  a  portable  graymap into a portable
       bitmap

SYNOPSIS
       pgmtopbm  [-floyd|-fs|-threshold   |-dither8|-d8|-cluster3
       |-c3|-cluster4|-c4 |-cluster8|-c8] [-value val] [pgmfile]

DESCRIPTION
       Reads  a  portable  graymap as input.  Produces a portable
       bitmap as output.

       Note that there is no pbmtopgm converter, because any  pgm
       program can read pbm files automagically.

OPTIONS
       The  default quantization method is boustrophedonic Floyd-
       Steinberg error diffusion (-floyd or -fs).  Also available
       are  simple  thresholding  (-threshold);  Bayer's  ordered
       dither (-dither8) with a 16x16 matrix; and three different
       sizes of 45-degree clustered-dot dither (-cluster3, -clus-
       ter4, -cluster8).

       Floyd-Steinberg will almost always give the  best  looking
       results;  however,  looking  good  is  not always what you
       want.   For  instance,  thresholding  can  be  used  in  a
       pipeline  with the pnmconvol tool, for tasks like edge and
       peak detection.  And clustered-dot dithering gives a news-
       paper-ish look, a useful special effect.

       The  -value  flag alters the thresholding value for Floyd-
       Steinberg and simple thresholding.  It should  be  a  real
       number  between  0  and 1.  Above 0.5 means darker images;
       below 0.5 means lighter.

       All flags can be abbreviated to their shortest unique pre-
       fix.

REFERENCES
       The  only  reference  you  need for this stuff is "Digital
       Halftoning"  by   Robert   Ulichney,   MIT   Press,   ISBN
       0-262-21009-6.

SEE ALSO
       pbmreduce(1), pgm(5), pbm(5), pnmconvol(1)

AUTHOR
       Copyright (C) 1989 by Jef Poskanzer.









                           26 July 1988                         1