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.\" RCSid "$Id: phisto.1,v 1.3 2007/09/04 17:36:40 greg Exp $"
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greg |
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.TH PHISTO 1 3/12/98 RADIANCE
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.SH NAME
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phisto - compute a luminance histogram from one or more RADIANCE pictures
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.SH SYNOPSIS
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.B phisto
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.B "picture .."
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.SH DESCRIPTION
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.I Phisto
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is a script that calls
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.I pfilt(1),
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.I rcalc(1)
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and
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.I histo(1)
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to compute a histogram of log luminance values for foveal samples in
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the given picture files.
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A foveal sample covers approximately 1 degree, though this script does
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not use this exact area.
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The minimum and maximum values are determined, and 100 histogram bins
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are uniformly divided between these extrema.
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Foveal samples less than 1e-7 candelas/sq.meter are silently ignored.
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If no picture is named on the command line, the standard input is read.
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.PP
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The primary function of this script is to precompute histograms for the
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.I pcond(1)
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program, which may then be used to compute multiple, identical exposures.
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This is especially useful for animations and image comparisons.
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.SH EXAMPLE
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.PP
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greg |
1.4 |
To compute two identical tone mappings for image1.hdr and image2.hdr:
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greg |
1.1 |
.IP "" .2i
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greg |
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phisto image1.hdr image2.hdr > both.histo
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greg |
1.1 |
.br
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greg |
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pcond \-I \-h image1.hdr < both.histo > image1m.hdr
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greg |
1.1 |
.br
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greg |
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pcond \-I \-h image2.hdr < both.histo > image2m.hdr
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greg |
1.1 |
.SH AUTHOR
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Greg Ward Larson
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.SH "SEE ALSO"
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histo(1), pcond(1), pfilt(1), pvalue(1), rcalc(1), total(1)
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