.\" RCSid "$Id"
.TH RA_PR 1 11/15/93 RADIANCE
.SH NAME
ra_pr - convert RADIANCE picture to/from pixrect rasterfile
.SH SYNOPSIS
.B ra_pr
[
.B \-d
][
.B \-b
][
.B "\-c ncolors"
][
.B "\-g gamma"
][
.B "\-e +/-stops"
]
.B input
[
.B output
]
.br
.B ra_pr
.B \-r
[
.B "\-g gamma"
][
.B "\-e +/-stops"
]
[
.B input
[
.B output
]
]
.SH DESCRIPTION
.I Ra_pr
converts between RADIANCE and pixrect rasterfile formats.
In the default mode, a RADIANCE picture is converted to a pixrect
rasterfile of the same horizontal and vertical dimensions with
8-bits per pixel.
The
.I \-d
option turns off dithering.
The
.I \-b
option converts the image to black and white, for improved quality
on greyscale monitors.
Only with this option can the input be taken from stdin.
The
.I \-c
option allows fewer than 256 colors.
The
.I \-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
.I \-e
option specifies an exposure compensation in f-stops (powers of two).
Only integer stops are allowed, for efficiency.
The
.I \-r
option invokes a reverse conversion, from a pixrect rasterfile to
a RADIANCE picture.
If the output file is missing, the standard output is used.
.SH AUTHORS
Greg Ward
.br
Paul Heckbert provided the code for color quantization
.SH BUGS
Only standard 8-bit color rasterfiles are read or written.
.SH "SEE ALSO"
pfilt(1), ra_bn(1), ra_ppm(1), ra_pr24(1), ra_t8(1), ra_t16(1),
ra_tiff(1), ximage(1)