Ppmtoxpm User Manual(0) Ppmtoxpm User Manual(0)NAMEppmtoxpm - convert a PPM image to an X11 pixmap
SYNOPSISppmtoxpm [-name=xpmname] [-hexonly] [-rgb=rgb-textfile]
[-alphamask=pgmfile] [ppmfile]
Minimum unique abbreviation of option is acceptable. You may use dou‐
ble hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate an option name from
its value.
DESCRIPTION
This program is part of Netpbm(1).
ppmtoxpm reads a PPM image as input and produces X11 pixmap (version 3)
as output. This format can be loaded by the XPM library.
In the XPM output, colors may be identified by name, such as "Red", or
in hexadecimal, for example "#FF0000". In the hexadecimal format,
there may be from 1 through 4 hexadecimal digits per RGB component.
By default, ppmtoxpbm tries to find a name for each color in the image
in the system color dictionary ⟨libppm.html#rgb.txt⟩ , and if it finds
one, uses it. If it doesn't it uses hexadecimal. You can force ppm‐
toxpbm to use hexadecimal only with the -hexonly option. You can spec‐
ify a different color dictionary with the -rgb option.
When ppmtoxpm uses the hexadecimal format for identifying a color, it
uses the one that uses the least number of hexadecimal digits that it
takes to represent the maxval of the input PPM. E.g. if the maxval of
the input PPM is 100, ppmtoxpm uses 2 digits per component, as in
"#FF0000".
Some programs do not properly handle one-digit-per-component hexadeci‐
mal color specifiers. They see the wrong colors. To produce an XPM
that such a program can handle, make sure the maxval of the input PPM
is greater than 15, such as by running it through pamdepth 255.
Color Code Lengths - Image Size
In the XPM format, there is a palette ('color map') that assigns each
color in the image to a unique sequence of printable characters called
a color code, and a raster that identifies the color of each pixel of
the image with one of those color codes. The length of the color code
affects the size of the image stream.
All color codes in an image are the same length, and ppmtoxpm tries to
make it as short as possible. That length is, of course, determined by
the number of colors in the image. ppmtoxpm counts the colors in the
image, excluding those that will be transparent in the output due to
your alpha mask, and chooses a color code length accordingly. There
are 92 printable characters that can be used in a color code. There‐
fore, if you have 92 or fewer colors, your color codes will be one
character. If you have more than 92 but not more than 92 * 92, your
color codes will be two characters. And so on.
There's one exception to the above: If you specify an alpha mask (the
-alpha option, one unique color code represents 'transparent.' This is
true even if the alpha mask doesn't actually produce any transparent
pixels. So subtract one from the number of possible colors if you use
-alpha.
OPTIONS
-name=xpmname
This option specifies the prefix string which is specified in
the resulting XPM output. If you don't use the -name otpion,
ppmtoxpm defaults to the filename (without extension) of the
ppmfile parameter. If you do not specify -name or ppmfile (i.e.
your input is from Standard Input), the prefix string defaults
to the string noname.
-hexonly
This option says never to put color names in the XPM file, but
rather to identify names by hexadecimal strings that explicitly
identify RGB component intensities. This means the reader of
the file need not have access to a suitable color dictionary to
interpret it.
This option was introduced in Netpbm 10.15 (April 2003). Before
that, it was the default, overridden by specifying -rgb.
-rgb=rgb-textfile
This option names the file in which the color dictionary you
want to use resides. By default, ppmtoxpm uses the system color
dictionary ⟨libppm.html#rgb.txt⟩ .
This option in meaningless when you specify -hexonly.
Before Netpbm 10.15 (April 2003), ppmtoxpm did not default to
the system color dictionary. If you didn't specify -rgb, ppm‐
toxpbm would use only hexadecimal color specifiers.
-alphamask=pgmfile
This option names a PGM file to use as an alpha (transparency)
mask. The file must contain an image the same dimensions as the
input image. ppmtoxpm marks as transparent any pixel whose
position in the alpha mask image is at most half white.
If you don't specify -alphamask, ppmtoxpm makes all pixels in
the output opaque.
ppmcolormask is one way to generate an alpha mask file. You
might also generate it by extracting transparency information
from an XPM file with the -alphaout option to xpmtoppm.
There are similar options on other Netpbm converters that con‐
vert from formats that include transparency information too.
SEE ALSOppmcolormask(1), xpmtoppm(1), pamdepth(1), ppm(1) XPM Manual by Arnaud
Le Hors lehors@mirsa.inria.fr
AUTHOR
Copyright (C) 1990 by Mark W. Snitily.
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted, pro‐
vided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in sup‐
porting documentation. This software is provided 'as is' without
express or implied warranty.
This tool was developed for Schlumberger Technologies, ATE Division,
and with their permission is being made available to the public with
the above copyright notice and permission notice.
Upgraded to XPM2 by Paul Breslaw, Mecasoft SA, Zurich, Switzerland
(paul@mecazh.uu.ch), November 8, 1990.
Upgraded to XPM version 3 by Arnaud Le Hors(lehors@mirsa.inria.fr),
April 9, 1991.
netpbm documentation Feb 22 2003 Ppmtoxpm User Manual(0)
