ra_ppm(1) [osx man page]

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)

RA_TIFF(1)						      General Commands Manual							RA_TIFF(1)

NAME

       ra_tiff - convert RADIANCE picture to/from a TIFF color or greyscale image

SYNOPSIS

       ra_tiff [ -z|-L|-l|-f|-w ][ -b ][ -e +/-stops ][ -g gamma ] { in.hdr|- } out.tif
       ra_tiff -r [ -x ][ -g gamma ][ -e +/-stops ] in.tif [ out.hdr|- ]

DESCRIPTION

       Ra_tiff converts between RADIANCE and TIFF image formats.  The -g option specifies the exponent used in gamma correction; the default value
       is 2.2, which is the recommended value for TIFF images.

       The -b option can be used to specify an 8-bit greyscale TIFF output file.  The type of input file is determined automatically.

       The -z option will result in LZW compression of the TIFF output file.  The -L option specifies SGILOG compression, which is recommended	to
       capture	the  full dynamic range of the Radiance picture.  However, since many TIFF readers do not yet support this format, use this option
       under advisement.  The -l option specifies SGILOG24 compressed output, which has less dynamic range than SGILOG, but may be smaller in some
       cases.	(It is usually larger.)  The -f option specifies 32-bit IEEE floating-point/primary output, which is the highest resolution format
       but results in very large files, since each RGB pixel takes 96 bits (12 bytes) and  does  not  compress	well.	The  -w  option  specifies
       16-bit/primary  output, which is understood by some photo editing software, such as Adobe Photoshop.  Decompression is automatically deter-
       mined for TIFF input.

       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 TIFF image to a RADIANCE picture.  The RADIANCE picture file can be taken from the stan-
       dard  input or sent to the standard output by using a hyphen ('-') in place of the file name, but the TIFF image must be to or from a file.
       The -x option can be used to specify an XYZE Radiance output file, rather than the default RGBE.

EXAMPLES

       To convert a Radiance picture to SGILOG-compressed TIFF format:

	 ra_tiff -L scene1.hdr scene1.tif

       To later convert this image back into Radiance and display using human visibility tone-mapping:

	 ra_tiff -r scene1.tif scene1.hdr
	 ximage -e human scene1.hdr

AUTHOR

       Greg Ward Larson
       Sam Leffler

ACKNOWLEDGEMENT

       Work on this program was initiated and sponsored by the LESO group at EPFL in Switzerland.  Additions for the  SGILOG  data  encoding  were
       sponsored by Silicon Graphics, Inc.

BUGS

       Many TIFF file subtypes are not supported.
       A gamma value other than 2.2 is not properly recorded or understood if recorded in the TIFF file.

SEE ALSO

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

RADIANCE
							      8/29/97								RA_TIFF(1)