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]
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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.
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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.
42 -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.
50 -msb2lsb,-lsb2msb
53 These options control fill order (default is -msb2lsb).
54 -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.
61 -lowdotrange,-highdotrange
64 These options set tag values that may be useful for printers.
65 -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.
70 -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.
73 -konly sets all inks to the normal black value.
75 -default,-negative
78 These options control what ink levels pnmtotiffcmyk uses to represent
79 each input color.
80 -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.
85 -default is not necessary, unless you have to countermand a -negative
87 on the same command line.
88 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.
94 The options below modify this conversion.
96 -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.
106 -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.
115 -gammap n
118 This option controls the black replacement.
119 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.
124 Values of n from 0.01 to 10 are valid.
126 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.
130 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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139 pamtotiff(1), tifftopnm(1), pnm(1)
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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.
146 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:
152 Derived by Jef Poskanzer from ras2tif.c, which is:
155 Copyright (c) 1990 by Sun Microsystems, Inc.
157 Author: Patrick J. Naughton naughton@wind.sun.com
159 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.
165 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.
172
175 This manual page was generated by the Netpbm tool 'makeman' from HTML
176 source. The master documentation is at
177 http://netpbm.sourceforge.net/doc/pnmtotiffcmyk.html
179netpbm documentation 21 March 2017 Pnmtotiffcmyk User Manual(0)