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1 perry 1 pnmtotiffcmyk
2 !!!pnmtotiffcmyk
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 OPTIONS
7 BUGS
8 SEE ALSO
9 AUTHOR
10 ----
11 !!NAME
12
13
14 pnmtotiffcmyk - convert a a portable anymap into a CMYK encoded TIFF file
15 !!SYNOPSIS
16
17
18 __pnmtotiffcmyk__
19 [[__Compargs__][[__Tiffargs__][[__Convargs__][[
20 ''pnmfile'' ]
21
22
23 Compargs:
24
25
26 [[__-none__|__-packbits__|__-lzw__
27 [[__-predictor__ ''n'']]
28
29
30 Tiffargs:
31
32
33 [[__-msb2lsb__|__-lsb2msb__] [[__-rowsperstrip__
34 ''n'']
35 [[__-lowdotrange__ ''n''] [[__-highdotrange__
36 ''n'']
37 [[__-knormal__|__-konly__|__-kremove__]
38
39
40 Convargs:
41
42
43 [[[[__-default__][[__Defargs__]|__-negative__]
44
45
46 Defargs:
47
48
49 [[__-theta__ ''deg''] [[__-gamma__ ''n'']
50 [[__-gammap__ ''-1''|__-gammap__
51 ''n'']
52 !!DESCRIPTION
53
54
55 Reads a portable anymap as input. Produces a CMYK encoded
56 TIFF file as output. Optionally modifies the colour balance
57 and black level, and removes CMY from under K.
58 !!OPTIONS
59
60
61 The order of most options is not important, but options for
62 particular conversion algorithms must appear after the
63 algorithm is selected (__-default__,__-negative__). If
64 no algorithm is selected then __-default__ is assumed and
65 the appropriate options
66 (__-theta__,__-gamma__,__-gammap__) can appear
67 anywhere.
68
69
70 __-none__,__-packbits__,__-lzw__,__-predictor__
71
72
73 Tiff files can be compressed. By default LZW decompression
74 is used, but (apparently) some readers cannot read this, so
75 you may want to select a different algorithm
76 (__-none__,__-packbits__). For LZW compression, a
77 __-predictor__ value of 2 forces horizontal differencing
78 of scanlines before encoding; a value of 1 forces no
79 differencing.
80
81
82 __-msb2lsb__,__-lsb2msb__
83
84
85 These flags control fill order (default is
86 __-msb2lsb__).
87
88
89 __-rowsperstrip__
90
91
92 This sets the number of rows in an image strip (data in the
93 Tiff files generated by this program is stored in strips -
94 each strip is compressed individually). The default gives a
95 strip size of no more than 8 kb.
96
97
98 __-lowdotrange__,__-highdotrange__
99
100
101 These options set tag values that may be useful for
102 printers. They have not been tested.
103
104
105 __-knormal__,__-kremove__,__-konly__
106
107
108 These options modify the values written to the Tiff file
109 after the conversion calculations (described below) are
110 completed. They are useful only for testing and debugging
111 the code.
112
113
114 __-kremove__ sets the black (K) layer to zero while
115 __-konly__ sets all inks to the black value.
116
117
118 __-default__,__-negative__
119
120
121 __-negative__ selects a simple algorithm that generates a
122 colour negative. None of the following options apply to this
123 algorithm, which is included as an example in the source to
124 help implementors of other conversions. __-default__ is
125 not needed, unless it is used to countermand a
126 __-negative__ on the same command line. The default
127 conversion from RGB to CMYK can be modified by altering the
128 options listed below.
129
130
131 The CMYKTiff web site includes tests on the conversion
132 parameters. The test images illustrate the command line
133 options in practice and may make the following explanation
134 clearer.
135
136
137 __-theta__ ''deg''
138
139
140 The basic conversion from RGB to CMY uses C = 1-R, M = 1-G,
141 Y = 1-B. __-theta__ provides a simple correction for any
142 colour bias that may occur in the printed image because, in
143 practice, inks do not exactly complement the primary
144 colours. It rotates the colours by the amount given
145 (''deg'') in degrees. Unless you are trying to produce
146 unusual effects you will need to use small values (try
147 generating three images at -10, 0 (the default) and 10
148 degrees and seeing which has the best colour
149 balance.
150
151
152 __-gamma__ ''n''
153
154
155 The black (K) component of the image is calculated as
156 min(C,Y,M). __-gamma__ applies a gamma correction to this
157 level. In other words, the final black level is K
158 (normalised to the range 0 to 1) raised to the ''n''th
159 power. In practice this means that a value greater than 1
160 makes the image lighter and a value less than 1 makes the
161 image darker. The range of allowed values is 0.1 to
162 10.
163
164
165 __-gammap__ ''n''
166
167
168 This option controls the removal of CMY under K. If ''n''
169 is -1 then no removal occurs and C, M, Y and K are
170 calculated as above. This means that, when printed, dark
171 areas contain all four inks, which can make high contrast
172 areas, like lettering, appear fuzzy.
173
174
175 By default, when __-gammap__ is not given on the command
176 line, the colours are reduced in dark areas by subtracting
177 the black level. The value subtracted is calculated with the
178 same gamma correction given by __-gamma__. Hopefully this
179 will reduce fuzziness without changing the appearance of the
180 image significantly.
181
182
183 If __-gammap__ ''n'' is given, with n between 0.01 and
184 10, then black is still subtracted, but the subtracted value
185 is calculated using ''n'' rather than any value supplied
186 with __-gamma__. For example, it may be best to only
187 subtract black from the coloured inks in the very darkest
188 regions. In that case, ''n'' should be a large value,
189 such as 5.
190 !!BUGS
191
192
193 This program is not self-contained. It must be used with
2 perry 194 !NetPbm and libtiff must be available (libtiff is included in
195 the 1mar94 release of !NetPbm).
1 perry 196 !!SEE ALSO
197
198
199 pnmtotiff(1), tifftopnm(1), pnm(5)
200 !!AUTHOR
201
202
203 Copyright (c) 1999 Andrew Cooke (Jara Software). Released
204 under the GPL with no warranty. See source or COPYRIGHT and
205 LICENCE files in distribution for full details.
206
207
208 Much of the code (and man page!) uses ideas from other pnm
209 programs, written by Jef Poskanzer (thanks go to him and
210 libtiff maintainer Sam Leffler). A small section of the code
211 - some of the tiff tag settings - is derived directly from
212 pnmtotiff, by Jef Poskanzer, which, in turn, acknowledges
213 Patrick Naughton with the following text:
214
215
216 Derived by Jef Poskanzer from ras2tif.c, which
217 is:
218
219
220 Copyright (c) 1990 by Sun Microsystems, Inc.
221
222
223 Author: Patrick J. Naughton
224 naughton@wind.sun.com
225
226
227 Permission to use, copy, modify, and distribute this
228 software and its documentation for any purpose and without
229 fee is hereby granted, provided that the above copyright
230 notice appear in all copies and that both that copyright
231 notice and this permission notice appear in supporting
232 documentation.
233
234
235 This file is provided AS IS with no warranties of any kind.
236 The author shall have no liability with respect to the
237 infringement of copyrights, trade secrets or any patents by
238 this file or any part thereof. In no event will the author
239 be liable for any lost revenue or profits or other special,
240 indirect and consequential damages.
241 ----
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