php man page for ra_ppm

RA_PPM(1)						      General Commands Manual							 RA_PPM(1)

NAME

       ra_ppm - convert RADIANCE picture to/from a Poskanzer Portable Pixmap

SYNOPSIS

       ra_ppm [ -r ][ -a ][ -b ][ -s maxv ][ -g gamma ][ -e +/-stops ] [ input [ output ] ]

DESCRIPTION

       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  conver-
       sion  is  much  slower,	which is why this format is not normally used.	The -b option forces greyscale output.	The -s option controls the
       output scale, which is 255 by default.  If this value is set above 255, then two bytes will be output for each component  in  binary  mode.
       This  may  not  be understood by some PPM readers, which do not understand files with maximum values greater than 255.  The maximum allowed
       setting for this parameter is 65535.

       With the -r option, the type of the Pixmap input file is determined automatically.  Ra_ppm will read either  greyscale  or  color  Pixmaps,
       with any precision up to a maximum scale of 65535.

NOTES

       The  Poskanzer  Portable  Bitmap  Plus package contains translators between the Pixmap format and many of the dozen or so image file "stan-
       dards" 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".

AUTHOR

       Greg Ward

ACKNOWLEDGEMENT

       Work on this program was initiated and sponsored by the LESO group at EPFL in Switzerland and Silicon Graphics, Inc.

SEE ALSO

       pfilt(1), ra_bmp(1), ra_bn(1), ra_pr(1), ra_pr24(1), ra_t8(1), ra_t16(1), ra_tiff(1), ximage(1)

RADIANCE
							      2/10/99								 RA_PPM(1)