Radiance normtiff program

NORMTIFF(1)                                                        NORMTIFF(1)

NAME

       normtiff  -  tone-map and convert RADIANCE picture or HDR TIFF to stan-
       dard TIFF

SYNOPSIS

       normtiff [ options ] input output.tif

DESCRIPTION

       Normtiff prepares a Radiance picture or  high  dynamic-range  TIFF  for
       output  to  a display or hard copy device.  If the dynamic range of the
       scene exceeds that of the display (as is usually  the  case),  normtiff
       will  compress the dynamic range of the picture such that both dark and
       bright regions are visible.  In addition, certain limitations in  human
       vision may be mimicked in order to provide an appearance similar to the
       experience one might have in the actual scene.

       Output is always an uncompressed RGB TIFF, which must be named  on  the
       command line along with the input file.  If the input file has a ".tif"
       or ".tiff" extension, normtiff attempts to read it as a  TIFF.   Other-
       wise, normtiff first tries opening it as a RADIANCE picture, only open-
       ing it as a TIFF if it fails header inspection.   (See  the  getinfo(1)
       program.)   If  the  input  is  neither  a  RADIANCE picture nor a high
       dynamic-range TIFF, the program reports an error and exits.

       The following command line options are understood.  Since this  program
       is very similar to pcond(1), several of the switches are identical.

       -b        Toggle 8-bit black and white (grayscale) TIFF output.  If the
                 input is a  grayscale  TIFF,  this  switch  is  automatically
                 selected.  Otherwise, the output defaults to 24-bit RGB.

       -z        Output LZW-compressed TIFF (smaller file).

       -h        Mimic  human visual response in the output.  The goal of this
                 process is to produce output that correlates strongly with  a
                 person's subjective impression of a scene.  This switch turns
                 on both the -s and -c switches, described below.

       -s        Toggle the use of the human contrast sensitivity function  in
                 determining  the exposure for the image.  A darker scene will
                 have relatively lower exposure with  lower  contrast  than  a
                 well-lit scene.

       -c        Toggle  mesopic  color correction.  If parts of the image are
                 in the mesopic or scotopic range where the  cone  photorecep-
                 tors  lose  their efficiency, this switch will cause a corre-
                 sponding loss of color visibility in the output and  a  shift
                 to a scotopic (blue-dominant) response function.

       -l        Toggle the use of a linear response function versus the stan-
                 dard dynamic range compression algorithm.  This may make some
                 parts of the resulting image too dark or too bright to see.

       -u Ldmax  Specifies  the top of the luminance range for the target out-
                 put device.  That is, the luminance (in candelas/m^2) for  an
                 output  pixel value of (R,G,B)=(255,255,255).  This parameter
                 affects tone mapping only when the  -s  switch  is  on.   The
                 default value is 100 cd/m^2.

       -d Lddyn  Specifies  the  dynamic  range  for the target output device,
                 which is the ratio of the maximum and minimum usable  display
                 luminances.   The  default  value is 32, which is typical for
                 CRT monitors.

       -p xr yr xg yg xb yb xw yw
                 Specifies the RGB primaries for  the  target  output  device.
                 These  are  the  1931  CIE (x,y) chromaticity values for red,
                 green, blue and white, respectively.

       -g gamma  Specifies the output  device  gamma  correction  value.   The
                 default value is 2.2, which is appropriate for most CRT moni-
                 tors.  (A value of 1.8 is common in color prepress and  color
                 printers.)

EXAMPLES

       To convert a RADIANCE picture to an 8-bit grayscale TIFF:

         normtiff -b scene.hdr sceneb.tif

       To  condition  a high dynamic-range TIFF for a particular film recorder
       with known color primaries, dynamic range and gamma response:

         pcond -d 50 -g 2.5 -p  .580  .340  .281  .570  .153  .079  .333  .333
         orig.tif filmrgb.tif

       To simulate human visual response on a monitor with known maximum lumi-
       nance:

         normtiff -h -u 80 scene.hdr sceneh.tif

REFERENCE

       Greg Ward Larson, Holly Rushmeier,  Christine  Piatko,  ``A  Visibility
       Matching  Tone  Reproduction  Operator for High Dynamic Range Scenes,''
       IEEE Transactions on Visualization and  Computer  Graphics  ,  December
       1997.

       http://positron.cs.berkeley.edu/gwlarson/pixformat/

AUTHOR

       Greg Ward Larson

ACKNOWLEDGMENT

       This work was supported by Silicon Graphics, Inc.

SEE ALSO

       getinfo(1),  pcond(1),  pflip(1),  pvalue(1),  protate(1),  ra_xyze(1),
       rpict(1), ximage(1)

RADIANCE                            2/25/99                        NORMTIFF(1)