PHISTO(1)                                                            PHISTO(1)



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

SSYYNNOOPPSSIISS
       pphhiissttoo ppiiccttuurree ....

DDEESSCCRRIIPPTTIIOONN
       _P_h_i_s_t_o is a script that calls _p_f_i_l_t_(_1_)_, _r_c_a_l_c_(_1_) and _h_i_s_t_o_(_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
       _p_c_o_n_d_(_1_) program, which may then be used to compute multiple, identical
       exposures.   This is especially useful for animations and image compar-
       isons.

EEXXAAMMPPLLEE
       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

AAUUTTHHOORR
       Greg Ward Larson

SSEEEE AALLSSOO
       histo(1), pcond(1), pfilt(1), pvalue(1), rcalc(1), total(1)



RADIANCE                            3/12/98                          PHISTO(1)
