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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18

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       In  addition  to  the options common to all programs based on libnetpbm
38       (most notably -quiet, see
39        Common Options ⟨index.html#commonoptions⟩ ), pnmtotiffcmyk  recognizes
40       the following command line options:
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42       The  order of most options is not important, but options for particular
43       conversion algorithms must  appear  after  the  algorithm  is  selected
44       (-default,-negative).   If you don't select an algorithm, pnmtotiffcmyk
45       assumes -default and the  appropriate  options  (-theta,-gamma,-gammap)
46       can appear anywhere.
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48
49   -none,-packbits,-lzw,-predictor
50       Tiff  files  can  be  compressed.   By  default, pnmtotiffcmyk uses LZW
51       decompression, but (apparently) some readers cannot read this,  so  you
52       may  want  to  select a different algorithm (-none,-packbits).  For LZW
53       compression, a -predictor value of 2 forces horizontal differencing  of
54       scanlines before encoding; a value of 1 forces no differencing.
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56
57   -msb2lsb,-lsb2msb
58       These options control fill order (default is -msb2lsb).
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60
61   -rowsperstrip
62       This  sets the number of rows in an image strip (data in the Tiff files
63       generated by this program is stored in strips  -  each  strip  is  com‐
64       pressed  individually).  The default gives a strip size of no more than
65       8 kb.
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67
68   -lowdotrange,-highdotrange
69       These options set tag values that may be useful for printers.
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71
72   -knormal,-kremove,-konly
73       These options control the calculation of the CMYK ink levels.  They are
74       useful only for testing and debugging the code.
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76       -kremove  sets the black (K) levels to zero while leaving the other ink
77       levels as they would be if the black level were normal.
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79       -konly sets all inks to the normal black value.
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81
82   -default,-negative
83       These options control what ink levels pnmtotiffcmyk uses  to  represent
84       each input color.
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86       -negative  selects  a simple algorithm that generates a color negative.
87       None of the following options apply to this algorithm.   The  algorithm
88       is  included  as  an example in the source code to help implementors of
89       other conversions.
90
91       -default is not necessary, unless you have to countermand  a  -negative
92       on the same command line.
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94       The default conversion from RGB to CMYK is as follows: The basic values
95       of the 3 pigments are C = 1-R, M = 1-G, Y =  1-B.   From  this,  pnmto‐
96       tiffcmyk chooses a black (K) level which is the minimum of those three.
97       It then replaces that much of the 3 pigments with the black.   I.e.  it
98       subtracts K from each of the basic C, M, and Y values.
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100       The options below modify this conversion.
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102
103   -theta deg
104       -theta  provides  a simple correction for any color bias that may occur
105       in the printed image because, in practice, inks do not exactly  comple‐
106       ment  the primary colors.  It rotates the colors (before black replace‐
107       ment) by deg degrees in the color wheel.  Unless you are trying to pro‐
108       duce unusual effects you will need to use small values.  Try generating
109       three images at -10, 0 (the default) and 10 degrees and see  which  has
110       the best color balance.
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112
113   -gamma n
114       -gamma  applies  a  gamma  correction  to the black (K) value described
115       above.  Specifically, instead of calculating the K value as min(C,M,Y),
116       pnmtotiffcmyk raises that value (normalised to the range 0 to 1) to the
117       nth power.  In practice, this means that a value greater than  1  makes
118       the  image lighter and a value less than 1 makes the image darker.  The
119       range of allowed values is 0.1 to 10.
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121
122   -gammap n
123       This option controls the black replacement.
124
125       If you specify -gammap, pnmtotiffcmyk uses the specified gamma value in
126       computing  how  much  ink to remove from the 3 pigments, but still uses
127       the regular gamma value (-gamma option) to generate the  actual  amount
128       of black ink with which to replace it.
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130       Values of n from 0.01 to 10 are valid.
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132       For  example,  it  may  be best to only subtract black from the colored
133       inks in the very darkest regions.  In that case, n should  be  a  large
134       value, such as 5.
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136       As  a  special case, if n is -1, pnmtotiffcmyk does not remove any pig‐
137       ment (but still adds the black ink).  This means dark  areas  are  even
138       darker.   Furthermore,  when  printed,  dark areas contain a lot of ink
139       which can make high contrast areas, like lettering, appear fuzzy.  It's
140       hard to see what the utility of this is.
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SEE ALSO

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

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

180       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
181       source.  The master documentation is at
182
183              http://netpbm.sourceforge.net/doc/pnmtotiffcmyk.html
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185netpbm documentation             21 March 2017    Pnmtotiffcmyk User Manual(0)
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