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)

RADIANCE                                             2/25/99                                         NORMTIFF(1)