Ppmtobmp User Manual(0) Ppmtobmp User Manual(0)
ppmtobmp - convert a PPM image into a BMP file
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.
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
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
-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 termi-
nates. You can use pnmquant or ppmdither to reduce the number of colors in the
This identifies a file to use as the BMP palette (aka 'colormap'). In one BMP sub-
format, 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 com-
puting 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 con-
struct the palette yourself and use this option to tell ppmtobmp to use your pal-
This option does not control what colors are in the output. The colors in the out-
put 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 ppm-
tobmp 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
You may find pnmcolormap useful in generating the palette file. pamseq too.
This option was new in Netpbm 10.45 (December 2008).
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.
bmptoppm(1) , ppmtowinicon(1) , pnmquant(1) , ppmdither(1) , pnmremap(1) , ppm(1)
Copyright (C) 1992 by David W. Sanderson.
netpbm documentation 29 October 2008 Ppmtobmp User Manual(0)