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Pnmtotiffcmyk User Manual(0)			  Pnmtotiffcmyk	User Manual(0)

NAME
       pnmtotiffcmyk - convert a Netpbm	image into a CMYK encoded TIFF file

SYNOPSIS
       pnmtotiffcmyk	      [-none|-packbits|-lzw]	     [-predictor    n]
	    [-msb2lsb|-lsb2msb]	     [-rowsperstrip n]	     [-lowdotrange  n]
	    [-highdotrange n]	   [-knormal|-konly|-kremove]	   [[-default]
	       [-theta deg]
	       [-gamma n]
	       [-gammap	n]
	       [-negative]

DESCRIPTION
       This program is part of Netpbm(1).

       pnmtotiffcmykreads  a  PNM  image  as input and produces	a CMYK encoded
       TIFF file as output.  It	optionally  modifies  the  color  balance  and
       black level, and	modifies removal of CMY	from under K.

       Output  is  to  Standard	 Output, but unlike with most Netpbm programs,
       Standard	Output must be a seekable file.	 An ordinary file is fine, but
       you  cannot  pipe the output to another program.	 Furthermore, the pro-
       gram replaces any content currently in the file even if it  was	opened
       for appending.

       pamtotiff generates many	other kinds of TIFF files.

OPTIONS
       The  order of most options is not important, but	options	for particular
       conversion algorithms must appear after the algorithm is	selected (-de-
       fault,-negative).   If you don't	select an algorithm, pnmtotiffcmyk as-
       sumes -default and the appropriate options (-theta,-gamma,-gammap)  can
       appear anywhere.

   -none,-packbits,-lzw,-predictor
       Tiff  files  can	be compressed.	By default, pnmtotiffcmyk uses LZW de-
       compression, but	(apparently) some readers cannot read this, so you may
       want  to	 select	a different algorithm (-none,-packbits).  For LZW com-
       pression, a -predictor value of 2  forces  horizontal  differencing  of
       scanlines before	encoding; a value of 1 forces no differencing.

   -msb2lsb,-lsb2msb
       These options control fill order	(default is -msb2lsb).

   -rowsperstrip
       This  sets the number of	rows in	an image strip (data in	the Tiff files
       generated by this program is stored in strips  -	 each  strip  is  com-
       pressed	individually).	The default gives a strip size of no more than
       8 kb.

   -lowdotrange,-highdotrange
       These options set tag values that may be	useful for printers.

   -knormal,-kremove,-konly
       These options control the calculation of	the CMYK ink levels.  They are
       useful only for testing and debugging the code.

       -kremove	 sets the black	(K) levels to zero while leaving the other ink
       levels as they would be if the black level were normal.

       -konly sets all inks to the normal black	value.

   -default,-negative
       These options control what ink levels pnmtotiffcmyk uses	 to  represent
       each input color.

       -negative  selects  a simple algorithm that generates a color negative.
       None of the following options apply to this algorithm.	The  algorithm
       is  included  as	 an example in the source code to help implementors of
       other conversions.

       -default	is not necessary, unless you have to countermand  a  -negative
       on the same command line.

       The default conversion from RGB to CMYK is as follows: The basic	values
       of the 3	pigments are C = 1-R, M	= 1-G, Y =  1-B.   From	 this,	pnmto-
       tiffcmyk	chooses	a black	(K) level which	is the minimum of those	three.
       It then replaces	that much of the 3 pigments with the black.   I.e.  it
       subtracts K from	each of	the basic C, M,	and Y values.

       The options below modify	this conversion.

   -theta deg
       -theta  provides	 a simple correction for any color bias	that may occur
       in the printed image because, in	practice, inks do not exactly  comple-
       ment  the primary colors.  It rotates the colors	(before	black replace-
       ment) by	deg degrees in the color wheel.	 Unless	you are	trying to pro-
       duce unusual effects you	will need to use small values.	Try generating
       three images at -10, 0 (the default) and	10 degrees and see  which  has
       the best	color balance.

   -gamma n
       -gamma  applies	a  gamma  correction  to the black (K) value described
       above.  Specifically, instead of	calculating the	K value	as min(C,M,Y),
       pnmtotiffcmyk raises that value (normalised to the range	0 to 1)	to the
       nth power.  In practice,	this means that	a value	greater	than  1	 makes
       the  image lighter and a	value less than	1 makes	the image darker.  The
       range of	allowed	values is 0.1 to 10.

   -gammap n
       This option controls the	black replacement.

       If you specify -gammap, pnmtotiffcmyk uses the specified	gamma value in
       computing  how  much  ink to remove from	the 3 pigments,	but still uses
       the regular gamma value (-gamma option) to generate the	actual	amount
       of black	ink with which to replace it.

       Values of n from	0.01 to	10 are valid.

       For  example,  it  may  be best to only subtract	black from the colored
       inks in the very	darkest	regions.  In that case,	n should  be  a	 large
       value, such as 5.

       As  a  special case, if n is -1,	pnmtotiffcmyk does not remove any pig-
       ment (but still adds the	black ink).  This means	dark  areas  are  even
       darker.	 Furthermore,  when  printed,  dark areas contain a lot	of ink
       which can make high contrast areas, like	lettering, appear fuzzy.  It's
       hard to see what	the utility of this is.

SEE ALSO
       pamtotiff(1), tifftopnm(1), pnm(5)

AUTHOR
       Copyright  (c)  1999  Andrew Cooke (Jara	Software).  Released under the
       GPL with	no warranty.  See source or COPYRIGHT  and  LICENCE  files  in
       distribution for	full details.

       Much  of	the code uses ideas from other Netpbm programs,	written	by Jef
       Poskanzer (thanks go to him and libtiff	maintainer  Sam	 Leffler).   A
       small  section of the code - some of the	tiff tag settings - is derived
       directly	from pnmtotiff,	by Jef Poskanzer, which, in turn, acknowledges
       Patrick Naughton	with the following text:

	      Derived by Jef Poskanzer from ras2tif.c, which is:

	      Copyright	(c) 1990 by Sun	Microsystems, Inc.

	      Author: Patrick J. Naughton naughton@wind.sun.com

	      Permission  to  use,  copy, modify, and distribute this software
	      and its documentation for	any purpose and	without	fee is	hereby
	      granted,	provided that the above	copyright notice appear	in all
	      copies and that both that	copyright notice and  this  permission
	      notice appear in supporting documentation.

	      This file	is provided AS IS with no warranties of	any kind.  The
	      author shall have	no liability with respect to the  infringement
	      of  copyrights, trade secrets or any patents by this file	or any
	      part thereof.  In	no event will the author  be  liable  for  any
	      lost  revenue  or	 profits or other special, indirect and	conse-
	      quential damages.

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/pnmtotiffcmyk.html

netpbm documentation		 21 March 2017	  Pnmtotiffcmyk	User Manual(0)

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

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