NAME

       normtiff - tone-map and convert RADIANCE picture or HDR TIFF to standard 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.  Otherwise, normtiff first tries opening it as  a  RADIANCE
       picture,  only  opening  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 photoreceptors lose their efficiency, this switch
                 will cause a corresponding 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 standard 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 output 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 monitors.  (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 luminance:

         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)