ra_t8 - convert RADIANCE picture to/from Targa 8-bit image file
−d ][ −b ][ −c
ncolors ][ −g gamma ][ −e
+/-stops ][ -n sampfac ] input [
ra_t8 −r [ −g gamma ][ −e +/-stops ] [ input [ output ] ]
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.
Anthony Dekker provided the code for neural network color quantization
Run-length encoded files can be read but not written with this program.
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)