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ra_ppm - convert RADIANCE picture to/from a Poskanzer
Portable Pixmap
ra_ppm [ -r ][ -a ][ -g gamma ][ -e +/-stops ] [ input [
output ] ]
Ra_ppm converts between RADIANCE and Poskanzer Portable
Pixmap formats. The -g option specifies the exponent used
in gamma correction; the default value is 2.2. An exponent
of 1 turns gamma correction off. The -e option specifies an
exposure compensation in f-stops (powers of two). Only
integer stops are allowed, for efficiency. The -r option
invokes a reverse conversion, from a Pixmap to a RADIANCE
picture. If the output file is missing, the standard output
is used. If the input file is missing as well, the standard
input is used.
The -a option produces a standard ASCII Pixmap
representation instead of the default binary file. The file
is much larger and the conversion is much slower, which is
why this format is not normally used.
With the -r option, the type of the Pixmap input file is
determined automatically. Ra_ppm will read either greyscale
or color Pixmaps, but will only produce color Pixmaps on
output.
The Poskanzer Portable Bitmap Plus package contains
translators between the Pixmap format and many of the dozen
or so image file "standards" that exist. At the time of
this writing, the software is free and available by
anonymous ftp from export.lcs.mit.edu (18.30.0.238) in the
file "contrib/pbmplus.tar.Z".
Greg Ward
Work on this program was initiated and sponsored by the LESO
group at EPFL in Switzerland.
pfilt(1), ra_bn(1), ra_pr(1), ra_pr24(1), ra_t8(1),
ra_t16(1), ra_tiff(1), ximage(1)
Header and Footer
RA_PPM(1) RADIANCE (11/15/93) RA_PPM(1)
Page 1 (printed 7/17/96)
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