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