NAME

       ra_t8 - convert RADIANCE picture to/from Targa 8-bit image file

SYNOPSIS

       ra_t8 [ -d ][ -b ][ -c ncolors ][ -g gamma ][ -e +/-stops ][ -n sampfac ] input [ output ]
       ra_t8 -r [ -g gamma ][ -e +/-stops ] [ input [ output ] ]

DESCRIPTION

       Ra_t8   converts  between  RADIANCE  and  Targa  8-bit  color-mapped  image  files  (type  1  in  Targa's
       documentation).  In the default mode, a RADIANCE picture is converted to a color-mapped Targa file of the
       same horizontal and vertical dimensions with 8-bits per pixel.  The -d option turns off  dithering.   The
       -b  option  converts  the  image  to  black and white.  Only with this option can the input be taken from
       stdin.  The -c option allows fewer than 256 colors.  The -g option specifies the exponent used  in  gamma
       correction;  the  default  value  is  2.2.  An exponent of 1.0 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 -n option specifies a sampling factor for neural network color quantization.  This value
       should be between 1 and 80, where 1 takes the longest and produces the best results in small areas of the
       image.   If  no  value  is given, a faster median cut algorithm is used.  The -r option invokes a reverse
       conversion, from an 8-bit Targa file to a RADIANCE picture.  If the output file is missing, the  standard
       output is used.

AUTHORS

       Greg Ward
       Anthony Dekker provided the code for neural network color quantization

BUGS

       Run-length encoded files can be read but not written with this program.

SEE ALSO

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

RADIANCE                                             5/30/95                                            RA_T8(1)