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greg |
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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 |
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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 |
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.br |
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greg |
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pcond \-I \-h image1.hdr < both.histo > image1m.hdr |
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greg |
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.br |
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greg |
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pcond \-I \-h image2.hdr < both.histo > image2m.hdr |
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greg |
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.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) |
