Radiance ra_tiff program

RA_TIFF(1)                                                          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/pri-
       mary output, which is understood by some photo editing  software,  such
       as Adobe Photoshop.  Decompression is automatically determined 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
       standard  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 spon-
       sored 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)