pnmtotiffcmyk
convert a portable anymap into a CMYK encoded TIFF file
see also :
pnmtotiff - tifftopnm
Synopsis
pnmtotiffcmyk
[Compargs][Tiffargs][Convargs][
pnmfile ]
Compargs:
[-none|-packbits|-lzw
[-predictor n]]
Tiffargs:
[-msb2lsb|-lsb2msb]
[-rowsperstrip n]
[-lowdotrange n]
[-highdotrange n]
[-knormal|-konly|-kremove]
Convargs:
[[-default][Defargs]|-negative]
Defargs:
[-theta
deg] [-gamma n]
[-gammap -1|-gammap
n]
add an example, a script, a trick and tips
examples
source
pnminterp pnmnoraw pnmscale pnmsplit pnmtofits
pnmtojpeg pnmtopnm pnmtops \\\
pnmtotiff pnmtotiffcmyk ppmnorm
ppmsvgalib ppmtojpeg ppmtotga ppmtouil \\\
source
pnminterp pnmnoraw pnmscale pnmsplit pnmtofits
pnmtojpeg pnmtopnm pnmtops \\\
pnmtotiff pnmtotiffcmyk ppmnorm
ppmsvgalib ppmtojpeg ppmtotga ppmtouil \\\
tifftopnm vidtoppm \
source
pnminterp pnmnoraw pnmscale pnmsplit pnmtofits
pnmtojpeg pnmtopnm pnmtops \\\
pnmtotiff pnmtotiffcmyk ppmnorm
ppmsvgalib ppmtojpeg ppmtotga ppmtouil \\\
description
Reads a
portable anymap as input. Produces a CMYK encoded TIFF file
as output. Optionally modifies the colour balance and black
level, and removes CMY from under K.
options
The order of
most options is not important, but options for particular
conversion algorithms must appear after the algorithm is
selected (-default,-negative). If
no algorithm is selected then -default is
assumed and the appropriate options
(-theta,-gamma,-gammap)
can appear anywhere.
-none,-packbits,-lzw,-predictor
Tiff files can be compressed.
By default LZW decompression is used, but (apparently) some
readers cannot read this, so you may want to select a
different algorithm
(-none,-packbits). For LZW
compression, a -predictor value of 2 forces
horizontal differencing of scanlines before encoding; a
value of 1 forces no differencing.
-msb2lsb,-lsb2msb
These flags control fill order
(default is -msb2lsb).
-rowsperstrip
This sets the number of rows in
an image strip (data in the Tiff files generated by this
program is stored in strips - each strip is compressed
individually). The default gives a strip size of no more
than 8 kb.
-lowdotrange,-highdotrange
These options set tag values
that may be useful for printers. They have not been
tested.
-knormal,-kremove,-konly
These options modify the values
written to the Tiff file after the conversion calculations
(described below) are completed. They are useful only for
testing and debugging the code.
-kremove
sets the black (K) layer to zero while -konly
sets all inks to the black value.
-default,-negative
-negative selects
a simple algorithm that generates a colour negative. None of
the following options apply to this algorithm, which is
included as an example in the source to help implementors of
other conversions. -default is not needed,
unless it is used to countermand a -negative on
the same command line. The default conversion from RGB to
CMYK can be modified by altering the options listed
below.
The CMYKTiff
web site includes tests on the conversion parameters. The
test images illustrate the command line options in practice
and may make the following explanation clearer.
-theta deg
The basic conversion from RGB
to CMY uses C = 1-R, M = 1-G, Y = 1-B. -theta
provides a simple correction for any colour bias that may
occur in the printed image because, in practice, inks do not
exactly complement the primary colours. It rotates the
colours by the amount given (deg) in degrees. Unless
you are trying to produce unusual effects you will need to
use small values (try generating three images at -10, 0 (the
default) and 10 degrees and seeing which has the best colour
balance.
-gamma n
The black (K) component of the
image is calculated as min(C,Y,M). -gamma
applies a gamma correction to this level. In other words,
the final black level is K (normalised to the range 0 to 1)
raised to the nth power. In practice this means that
a value greater than 1 makes the image lighter and a value
less than 1 makes the image darker. The range of allowed
values is 0.1 to 10.
-gammap n
This option controls the
removal of CMY under K. If n is -1 then no removal
occurs and C, M, Y and K are calculated as above. This means
that, when printed, dark areas contain all four inks, which
can make high contrast areas, like lettering, appear
fuzzy.
By default,
when -gammap is not given on the command line,
the colours are reduced in dark areas by subtracting the
black level. The value subtracted is calculated with the
same gamma correction given by -gamma.
Hopefully this will reduce fuzziness without changing the
appearance of the image significantly.
If
-gammap n is given, with n between
0.01 and 10, then black is still subtracted, but the
subtracted value is calculated using n rather than
any value supplied with -gamma. For example, it
may be best to only subtract black from the coloured inks in
the very darkest regions. In that case, n should be a
large value, such as 5.
bugs
This program is
not self-contained. It must be used with NetPbm and libtiff
must be available (libtiff is included in the 1mar94 release
of NetPbm).
see also
pnmtotiff ,
tifftopnm , pnm
author
Copyright (c)
1999 Andrew Cooke (Jara Software). Released under the GPL
with no warranty. See source or COPYRIGHT and LICENCE files
in distribution for full details.
Much of the
code (and man page!) uses ideas from other pnm programs,
written by Jef Poskanzer (thanks go to him and libtiff
maintainer Sam Leffler). A small section of the code - some
of the tiff tag settings - is derived directly from
pnmtotiff, by Jef Poskanzer, which, in turn, acknowledges
Patrick Naughton with the following text:
Derived by Jef
Poskanzer from ras2tif.c, which is:
Copyright (c)
1990 by Sun Microsystems, Inc.
Author: Patrick
J. Naughton naughton[:at:]wind.sun[:dot:]com
Permission to
use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in
all copies and that both that copyright notice and this
permission notice appear in supporting documentation.
This file is
provided AS IS with no warranties of any kind. The author
shall have no liability with respect to the infringement of
copyrights, trade secrets or any patents by this file or any
part thereof. In no event will the author be liable for any
lost revenue or profits or other special, indirect and
consequential damages.