1Pnmtotiffcmyk User Manual(0) Pnmtotiffcmyk User Manual(0)
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6 pnmtotiffcmyk - convert a Netpbm image into a CMYK encoded TIFF file
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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]
17
20 This program is part of Netpbm(1).
21 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.
25 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.
31 pamtotiff generates many other kinds of TIFF files.
33
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:
41 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.
47 -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.
55 -msb2lsb,-lsb2msb
58 These options control fill order (default is -msb2lsb).
59 -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.
66 -lowdotrange,-highdotrange
69 These options set tag values that may be useful for printers.
70 -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.
75 -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.
78 -konly sets all inks to the normal black value.
80 -default,-negative
83 These options control what ink levels pnmtotiffcmyk uses to represent
84 each input color.
85 -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 -default is not necessary, unless you have to countermand a -negative
92 on the same command line.
93 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.
99 The options below modify this conversion.
101 -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.
111 -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.
120 -gammap n
123 This option controls the black replacement.
124 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.
129 Values of n from 0.01 to 10 are valid.
131 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.
135 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.
141
144 pamtotiff(1), tifftopnm(1), pnm(1)
145
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 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:
157 Derived by Jef Poskanzer from ras2tif.c, which is:
160 Copyright (c) 1990 by Sun Microsystems, Inc.
162 Author: Patrick J. Naughton naughton@wind.sun.com
164 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 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.
177
180 This manual page was generated by the Netpbm tool 'makeman' from HTML
181 source. The master documentation is at
182 http://netpbm.sourceforge.net/doc/pnmtotiffcmyk.html
184netpbm documentation 21 March 2017 Pnmtotiffcmyk User Manual(0)