SYNOPSISra_gif [ -b ][ -d ][ -c ncolors ][ -g gamma ][ -e +/-stops ][ -n sampfac ] input [ output ]
DESCRIPTIONRa_gif converts from RADIANCE to Compuserve GIF color-mapped, compressed image files. In the default mode, a RADIANCE picture is converted to a color-mapped GIF file of the same horizontal and vertical dimensions with 8-bits per pixel. The -b option converts the image to black and white. The -d option turns off dithering. The -c option allows fewer than 256 colors (and fewer than 8 bits per pixel). 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. If the output file is missing, the standard output is used.
Anthony Dekker provided the code for neural network color quantization