Radiance phisto program

PHISTO(1)                                                            PHISTO(1)

NAME

       phisto  -  compute a luminance histogram from one or more RADIANCE pic-
       tures

SYNOPSIS

       phisto picture ..

DESCRIPTION

       Phisto is a script that calls pfilt(1), rcalc(1) and histo(1)  to  com-
       pute  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 maxi-
       mum 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 compar-
       isons.

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)

RADIANCE                            3/12/98                          PHISTO(1)