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 program replaces any content currently in the file even if it
       was opened for appending.

       pamtotiff generates many other kinds of TIFF files.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably -quiet,
       see
        Common  Options  ⟨index.html#commonoptions⟩  ),  pnmtotiffcmyk  recognizes  the following
       command line options:

       The order of most  options  is  not  important,  but  options  for  particular  conversion
       algorithms must appear after the algorithm is selected (-default,-negative).  If you don't
       select  an  algorithm,  pnmtotiffcmyk  assumes  -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 decompression, but
       (apparently) some readers cannot read  this,  so  you  may  want  to  select  a  different
       algorithm  (-none,-packbits).   For  LZW  compression,  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 compressed 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, pnmtotiffcmyk 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 complement the primary colors.  It rotates the
       colors (before black replacement) by deg degrees in  the  color  wheel.   Unless  you  are
       trying to produce 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 pigment (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(1)

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  consequential
              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