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ppmtorle - convert a PBMPLUS/ppm image file into an RLE image file.
ppmtorle [ -h ] [ -v ] [ -a ] [ -o outfile ] [ infile.ppm ]
This
program converts PBMPLUS full-color (ppm) image files into Utah RLE(5)
image
files. PBMPLUS/ppm image files contain the image dimensions and image data
in the form of RGB triplets. When converting to an RLE file, the alpha
channel may be optionally computed. The origins of PBMPLUS and Utah RLE
files are in the upper left and lower left corners respectively, so this
program automatically "flips" the image. The input can consist of several
concatenated ppm images, in which case, the output will consist of several
concatenated RLE images.
The RLE file will contain a "true color" image
(24 bits). These RLE files may then be viewed using any RLE image viewer.
When they are displayed on an 8 bit display, the image must be dithered.
In order to produce a better looking image (on 8 bit displays), it is
recommended that the image be quantizing (to 8 bit mapped color) prior
to its display. This may be done by piping the output of this program into
the Utah mcut(1)
or rlequant(1)
utilities. An example of this is shown later.
- -v
- This option will cause ppmtorle to operate in verbose mode. The
header information is written to "stderr". Actually, there is not much
header information stored in a PBMPLUS file, so this information is minimal.
- -h
- This option allows the header of the PBMPLUS image to be dumped to "stderr"
without converting the file. It is equivalent to using the -v option except
that no file conversion takes place.
- -a
- This option will cause ppmtorle to
use the RGB data to compute an alpha channel in the resulting RLE file.
For any non-zero RGB data, the alpha channel will contain a value of 255.
The resulting RLE image file will contain three color channels and an
alpha channel.
- -o outfile
- If specified, the output will be written to this
file. If outfile is "-", or if it is not specified, the output will be
written to the standard output stream.
- infile.ppm
- The name of the PBMPLUS
image data file to be converted. This file must end in ".ppm". However,
it is not necessary to supply the ".ppm" extension as it will be added to
the supplied name if not already there.
- ppmtorle -v test.ppm -o test.rle
- While running in verbose mode, convert test.ppm to RLE format and store
resulting data in test.rle.
- ppmtorle test | mcut >test.rle
- Convert test.ppm to
RLE format and convert to 8 bit mapped color before storing data in test.rle
- ppmtorle -h test
- Dump the header information of the PBMPLUS file called
test.ppm.
mcut(1)
, pgmtorle(1)
, rlequant(1)
, rletoppm(1)
, urt(1)
,
RLE(5)
.
Wesley C. Barris
Army High Performance Computing Research Center (AHPCRC)
Minnesota Supercomputer Center, Inc.
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