NAME

       ppmtobmp - convert a PPM image into a BMP file

SYNOPSIS

       ppmtobmp

       [-windows]

       [-os2]

       [-bpp=bits_per_pixel]

       [-mapfile=filename]

       [ppmfile]

       Minimum unique abbreviation of option is acceptable.  You may use double hyphens instead of single hyphen
       to  denote  options.  You may use white space in place of the equals sign to separate an option name from
       its value.

DESCRIPTION

       This program is part of Netpbm(1).

       ppmtobmp reads a PPM image as input and produces a Microsoft Windows or OS/2 BMP file as output.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably  -quiet,  see   Common
       Options ), ppmtobmp recognizes the following command line options:

       -windows
              Tells the program to produce a Microsoft Windows BMP file.  (This is the default.)

       -os2   Tells the program to produce an OS/2 BMP file.  (Before August 2000, this was the default).

       -bpp   This  tells  how  many  bits per pixel you want the BMP file to contain.  Only 1, 4, 8, and 24 are
              possible.  By default, ppmtobmp chooses the smallest number with which it can  represent  all  the
              colors  in  the input image.  If you specify a number too small to represent all the colors in the
              input image, ppmtobmp tells you and terminates.  You can use pnmquant or ppmdither to  reduce  the
              number of colors in the image.

              Before Netpbm 10.85 (December 2018), ppmtobmp ignores this option if the input is PBM and produces
              a  BMP  with  1  bit  per pixel.  With these versions, if you want more than that, use pbmtopgm to
              convert the PBM to PGM first.

       -mapfile=filename
              This identifies a file to use as the BMP palette (aka "colormap").  In one BMP subformat, the  BMP
              stream  contains  a  palette  of up to 256 colors, and represents the image raster as indices into
              that palette.  Normally, ppmtobmp takes care of computing a suitable palette, but if you are going
              to dissect the BMP output in some way, you may want certain values for the palette indices.   E.g.
              you  might want red to be 13, where ppmtobmp would (arbitrarily) choose 39.  In that case, you can
              construct the palette yourself and use this option to tell ppmtobmp to use your palette.

              This option does not control what colors are in the output.  The colors in the output are  exactly
              those  in  the  input, and the palette you supply must contain at least all the colors that are in
              the input.  You can use pnmremap to adjust your input image so that it contains only  colors  from
              your palette.

              The palette file is a Netpbm format file with one pixel per palette entry.  Each pixel must have a
              distinct  color (no repeats).  The order of the BMP palette ppmtobmp generates is the order of the
              pixels in the palette file, going from top to bottom, left to right.

              A BMP palette may have at most 256 colors, so the palette file must have at most 256 pixels.

              You may find pnmcolormap useful in generating the palette file.  pamseq too.

              In the case of grayscale image, if you are processing the BMP image, it
                may be convenient for you to have the actual gray values in the raster
                part of the image rather than arbitrary indices into a palette.  There is
                no BMP format specifically for that, but you can achieve it by using a
                palette in which each index is equal to the indexed gray value, and then
                ignoring the palette when you process the BMP image.

              Here is an example of doing that:

                  $ pamseq 1 255 > mapfile.pgm

                  $ ppmtobmp -mapfile=mapfile.pgm input.pgm > output.bmp

              This option was new in Netpbm 10.45 (December 2008).

NOTES

       To get a faithful reproduction of the input image, the maxval of the input image must be 255.  If  it  is
       something else, the colors in the BMP file may be slightly different from the colors in the input.

       Windows icons are not BMP files.  Use ppmtowinicon to create those.

SEE ALSO

       bmptoppm(1), ppmtowinicon(1), pnmquant(1), ppmdither(1), pnmremap(1), ppm(1)

AUTHOR

       Copyright (C) 1992 by David W. Sanderson.

DOCUMENT SOURCE

       This  manual  page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation
       is at

              http://netpbm.sourceforge.net/doc/ppmtobmp.html

netpbm documentation                            20 December 2018                         Ppmtobmp User Manual(1)