---
name: "ra_t8"
section: "1"
platform: "linux"
package: "radiance"
version: "4R1+20120125-1+b1"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/ra_t8"
---

# ra\_t8(1)

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

## 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)](/pfilt/1.md), [ra\_bmp(1)](/ra_bmp/1.md), ra\_bn(1), [ra\_ppm(1)](/ra_ppm/1.md), ra\_pr(1), ra\_pr24(1), [ra\_t16(1)](/ra_t16/1.md), [ra\_tiff(1)](/ra_tiff/1.md), [ximage(1)](/ximage/1.md)