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.\" RCSid "$Id$"
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.TH RA_PR 1 11/15/93 RADIANCE
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.SH NAME
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ra_pr - convert RADIANCE picture to/from pixrect rasterfile
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.SH SYNOPSIS
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.B ra_pr
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[
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.B \-d
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][
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.B \-b
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][
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.B "\-c ncolors"
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][
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.B "\-g gamma"
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][
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.B "\-e +/-stops"
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]
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.B input
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[
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.B output
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]
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.br
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.B ra_pr
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.B \-r
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[
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.B "\-g gamma"
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][
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.B "\-e +/-stops"
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]
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[
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.B input
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[
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.B output
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]
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]
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.SH DESCRIPTION
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.I Ra_pr
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converts between RADIANCE and pixrect rasterfile formats.
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In the default mode, a RADIANCE picture is converted to a pixrect
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rasterfile of the same horizontal and vertical dimensions with
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8-bits per pixel.
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The
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.I \-d
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option turns off dithering.
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The
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.I \-b
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option converts the image to black and white, for improved quality
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on greyscale monitors.
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Only with this option can the input be taken from stdin.
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The
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.I \-c
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option allows fewer than 256 colors.
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The
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.I \-g
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option specifies the exponent used in gamma correction;
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the default value is 2.2.
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An exponent of 1.0 turns gamma correction off.
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The
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.I \-e
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option specifies an exposure compensation in f-stops (powers of two).
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Only integer stops are allowed, for efficiency.
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The
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.I \-r
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option invokes a reverse conversion, from a pixrect rasterfile to
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a RADIANCE picture.
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If the output file is missing, the standard output is used.
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.SH AUTHORS
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Greg Ward
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.br
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Paul Heckbert provided the code for color quantization
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.SH BUGS
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Only standard 8-bit color rasterfiles are read or written.
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.SH "SEE ALSO"
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pfilt(1), ra_bn(1), ra_ppm(1), ra_pr24(1), ra_t8(1), ra_t16(1),
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ra_tiff(1), ximage(1)
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