1Pnmtotiffcmyk User Manual(0)                      Pnmtotiffcmyk User Manual(0)
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NAME

6       pnmtotiffcmyk - convert a Netpbm image into a CMYK encoded TIFF file
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SYNOPSIS

10       pnmtotiffcmyk          [-none|-packbits|-lzw]         [-predictor    n]
11            [-msb2lsb|-lsb2msb]      [-rowsperstrip n]       [-lowdotrange  n]
12            [-highdotrange n]      [-knormal|-konly|-kremove]      [[-default]
13               [-theta deg]
14               [-gamma n]
15               [-gammap n]
16               [-negative]
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DESCRIPTION

20       This program is part of Netpbm(1).
21
22       pnmtotiffcmykreads  a  PNM  image  as input and produces a CMYK encoded
23       TIFF file as output.  It optionally  modifies  the  color  balance  and
24       black level, and modifies removal of CMY from under K.
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26       Output  is  to  Standard  Output, but unlike with most Netpbm programs,
27       Standard Output must be a seekable file.  An ordinary file is fine, but
28       you  cannot  pipe the output to another program.  Furthermore, the pro‐
29       gram replaces any content currently in the file even if it  was  opened
30       for appending.
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32       pamtotiff generates many other kinds of TIFF files.
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OPTIONS

37       The  order of most options is not important, but options for particular
38       conversion algorithms must  appear  after  the  algorithm  is  selected
39       (-default,-negative).   If you don't select an algorithm, pnmtotiffcmyk
40       assumes -default and the  appropriate  options  (-theta,-gamma,-gammap)
41       can appear anywhere.
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44   -none,-packbits,-lzw,-predictor
45       Tiff  files  can  be  compressed.   By  default, pnmtotiffcmyk uses LZW
46       decompression, but (apparently) some readers cannot read this,  so  you
47       may  want  to  select a different algorithm (-none,-packbits).  For LZW
48       compression, a -predictor value of 2 forces horizontal differencing  of
49       scanlines before encoding; a value of 1 forces no differencing.
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51
52   -msb2lsb,-lsb2msb
53       These options control fill order (default is -msb2lsb).
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56   -rowsperstrip
57       This  sets the number of rows in an image strip (data in the Tiff files
58       generated by this program is stored in strips  -  each  strip  is  com‐
59       pressed  individually).  The default gives a strip size of no more than
60       8 kb.
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63   -lowdotrange,-highdotrange
64       These options set tag values that may be useful for printers.
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66
67   -knormal,-kremove,-konly
68       These options control the calculation of the CMYK ink levels.  They are
69       useful only for testing and debugging the code.
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71       -kremove  sets the black (K) levels to zero while leaving the other ink
72       levels as they would be if the black level were normal.
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74       -konly sets all inks to the normal black value.
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76
77   -default,-negative
78       These options control what ink levels pnmtotiffcmyk uses  to  represent
79       each input color.
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81       -negative  selects  a simple algorithm that generates a color negative.
82       None of the following options apply to this algorithm.   The  algorithm
83       is  included  as  an example in the source code to help implementors of
84       other conversions.
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86       -default is not necessary, unless you have to countermand  a  -negative
87       on the same command line.
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89       The default conversion from RGB to CMYK is as follows: The basic values
90       of the 3 pigments are C = 1-R, M = 1-G, Y =  1-B.   From  this,  pnmto‐
91       tiffcmyk chooses a black (K) level which is the minimum of those three.
92       It then replaces that much of the 3 pigments with the black.   I.e.  it
93       subtracts K from each of the basic C, M, and Y values.
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95       The options below modify this conversion.
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97
98   -theta deg
99       -theta  provides  a simple correction for any color bias that may occur
100       in the printed image because, in practice, inks do not exactly  comple‐
101       ment  the primary colors.  It rotates the colors (before black replace‐
102       ment) by deg degrees in the color wheel.  Unless you are trying to pro‐
103       duce unusual effects you will need to use small values.  Try generating
104       three images at -10, 0 (the default) and 10 degrees and see  which  has
105       the best color balance.
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107
108   -gamma n
109       -gamma  applies  a  gamma  correction  to the black (K) value described
110       above.  Specifically, instead of calculating the K value as min(C,M,Y),
111       pnmtotiffcmyk raises that value (normalised to the range 0 to 1) to the
112       nth power.  In practice, this means that a value greater than  1  makes
113       the  image lighter and a value less than 1 makes the image darker.  The
114       range of allowed values is 0.1 to 10.
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116
117   -gammap n
118       This option controls the black replacement.
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120       If you specify -gammap, pnmtotiffcmyk uses the specified gamma value in
121       computing  how  much  ink to remove from the 3 pigments, but still uses
122       the regular gamma value (-gamma option) to generate the  actual  amount
123       of black ink with which to replace it.
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125       Values of n from 0.01 to 10 are valid.
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127       For  example,  it  may  be best to only subtract black from the colored
128       inks in the very darkest regions.  In that case, n should  be  a  large
129       value, such as 5.
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131       As  a  special case, if n is -1, pnmtotiffcmyk does not remove any pig‐
132       ment (but still adds the black ink).  This means dark  areas  are  even
133       darker.   Furthermore,  when  printed,  dark areas contain a lot of ink
134       which can make high contrast areas, like lettering, appear fuzzy.  It's
135       hard to see what the utility of this is.
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SEE ALSO

139       pamtotiff(1), tifftopnm(1), pnm(1)
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AUTHOR

143       Copyright  (c)  1999  Andrew Cooke (Jara Software).  Released under the
144       GPL with no warranty.  See source or COPYRIGHT  and  LICENCE  files  in
145       distribution for full details.
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147       Much  of the code uses ideas from other Netpbm programs, written by Jef
148       Poskanzer (thanks go to him and libtiff  maintainer  Sam  Leffler).   A
149       small  section of the code - some of the tiff tag settings - is derived
150       directly from pnmtotiff, by Jef Poskanzer, which, in turn, acknowledges
151       Patrick Naughton with the following text:
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153
154              Derived by Jef Poskanzer from ras2tif.c, which is:
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156              Copyright (c) 1990 by Sun Microsystems, Inc.
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158              Author: Patrick J. Naughton naughton@wind.sun.com
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160              Permission  to  use,  copy, modify, and distribute this software
161              and its documentation for any purpose and without fee is  hereby
162              granted,  provided that the above copyright notice appear in all
163              copies and that both that copyright notice and  this  permission
164              notice appear in supporting documentation.
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166              This file is provided AS IS with no warranties of any kind.  The
167              author shall have no liability with respect to the  infringement
168              of  copyrights, trade secrets or any patents by this file or any
169              part thereof.  In no event will the author  be  liable  for  any
170              lost  revenue  or  profits or other special, indirect and conse‐
171              quential damages.
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DOCUMENT SOURCE

175       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
176       source.  The master documentation is at
177
178              http://netpbm.sourceforge.net/doc/pnmtotiffcmyk.html
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180netpbm documentation             21 March 2017    Pnmtotiffcmyk User Manual(0)
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