Manual: ppmtobmp

Ppmtobmp User Manual(1)				   General Commands Manual			     Ppmtobmp User Manual(1)

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 ter‐
	      minates.	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	con‐
	      tains  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 pn‐
	      mremap 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)