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Xwdtopnm User Manual(0)				       Xwdtopnm	User Manual(0)

NAME
       xwdtopnm	- convert an X11 or X10	window dump file to a PNM image

SYNOPSIS
       xwdtopnm	[-verbose] [-headerdump] [xwdfile]

DESCRIPTION
       This program is part of Netpbm(1).

       xwdtopnm	 reads	an X11 or X10 window dump file as input	and produces a
       PNM image as output.  The type of the output image depends on the input
       file  - if it's black and white,	the output is PBM.  If it's grayscale,
       the output is PGM.  Otherwise, it's PPM.	 The program tells  you	 which
       type it is writing.

       Using  this  program,  you can convert anything you can display on an X
       workstation's screen into a PNM image.  Just  display  whatever	you're
       interested  in, run the xwd program to capture the contents of the win-
       dow, run	it through xwdtopnm, and then use pamcut to  select  the  part
       you want.

       Note that a pseudocolor XWD image (typically what you get when you make
       a dump of a pseudocolor X window) has maxval 65535, which means the PNM
       file  that  xwdtopnm generates has maxval 65535.	 Many older image pro-
       cessing programs	(that aren't part of the Netpbm	package	and don't  use
       the  Netpbm  programming	 library) don't	know how to handle a PNM image
       with maxval greater than	255 (because there are two  bytes  instead  of
       one  for	 each sample in	the image).  So	you may	want to	run the	output
       of xwdtopnm through pamdepth before feeding it to one of	these old pro-
       grams.

       xwdtopnm	can't convert every kind of XWD	image (which essentially means
       it can't	convert	an XWD created from every kind of X display configura-
       tion).  In particular, it cannot	convert	one with more than 24 bits per
       pixel.

OPTIONS
       -verbose
	      This option causes xwdtopnm to display handy  information	 about
	      the input	image and the conversion process

       -headerdump
	      This  option  causes xwdtopnm to display the contents of the X11
	      header.  It has no effect	when the input is  X10.	  This	option
	      was new in Netpbm	10.26 (December	2004).

NOTES
   Two Byte Samples
       xwdtopnm	 sometimes  produces  output  with  a maxval greater than 255,
       which means the maximum value of	a sample (one  intensity  value,  e.g.
       the  red	 component  of a pixel)	is greater than	255 and	therefore each
       sample takes 2 bytes to represent.  This	can be a problem because  some
       programs	 expect	 those bytes in	a different order from what the	Netpbm
       format specs say, which is what xwdtopnm	 produces,  which  means  they
       will  see  totally  different colors that they should.	xv is one such
       program.

       If this is a problem (e.g. you want to look at the output  of  xwdtopnm
       with xv), there are two ways to fix it:

       o      Pass the output through pamendian	to produce the format the pro-
	      gram expects.

       o      Pass the output through pamdepth to reduce the maxval below  256
	      so there is only one byte	per sample.

       Often,  there  is no good reason	to have	a maxval greater than 255.  It
       happens because in XWD, byte not	PNM, each color	component of  a	 pixel
       can have	different resolution, for example 5 bits for blue (maxval 31),
       5 bits for red (maxval 31), and 6 bits for green	(maxval	63), for a to-
       tal  of 16 bits per pixel.  In order to reproduce the colors as closely
       as possible, xwdtopnm has to use	a large	maxval.	 In this  example,  it
       would use 31 * 63 = 1953, and use 48 bits per pixel.

       Because	this  is a common and frustrating problem when using xwdtopnm,
       the program issues a warning whenever it	generates output with two byte
       samples.	  You  can  quiet  this	 warning with the -quiet common	option
       <index.html#commonoptions> .  The  warning  was	new  in	 Netpbm	 10.46
       (March 2009).

SEE ALSO
       pnmtoxwd(1), pamendian(1), pamdepth(1), pnm(5), xwd man page

AUTHOR
       Copyright (C) 1989, 1991	by Jef Poskanzer.

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/xwdtopnm.html

netpbm documentation		8 January 2010	       Xwdtopnm	User Manual(0)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | SEE ALSO | AUTHOR | DOCUMENT SOURCE

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