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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 ( 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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