NAME

       pfsview - Viewer for high-dynamic range images in pfs format

SYNOPSIS

       pfsview [--window_min <log_lum>] [--window_max <log_lum>]

DESCRIPTION

       pfsview  is a QT application for viewing high-dynamic range images. It expects pfs stream on the standard
       input and displays the frames in that stream one by one.

       pfsv script can be more convienent to use if hdr images are to be displayed without any prior processing.

DYNAMIC RANGE WINDOW

       To show high-dynamic range data on a low-dynamic range monitor, pfsview uses concept of a  dynamic  range
       window. The dynamic range window is the highest and lowest value that should be mapped to black and white
       pixel.  Values  above  or  below  the  window are clipped (see clipping methods below). The dynamic range
       window is displayed in pfsview as a blue area on the dynamic range scale (second toolbox from  the  top).
       The window can be moved, shrunk and expended using a mouse or a keyboard.

CLIPPING METHODS

       Currently, two clipping methods are available (see View menu):

       Simple clipping
              The values above and below the dynamic range window are displayed as black or white.

       Color-coded clipping
              The  values  above the dynamic range window are displayed as yellow and below the window as green.
              This is helpful to see which parts of the image do not fit into the selected dynamic range.

       Keep brightness and hue
              This method tries to preserve brightness and hue  while  sacrificing  color  saturation  when  the
              colors  exceed  the  RGB  color  gamut.  Colors are desaturated in the RGB color space towards the
              neutral color (D65) of the corresponding luminance.

MAPPING METHODS

       High-dynamic range data are usually better visualized using non-linear scale, for example  a  logarithmic
       or  a  power function. pfsview offers several such scales, shown in View menu. Gray-scale values for each
       mapping method are computed by the formulas:

       LINEAR: y = (x-min)/(max-min)

       GAMMA: y = [ (x-min)/(max-min) ]^gamma

       LOGARITHMIC: y = (log10(x)-log10(min))/(log10(max)-log10(min))

       where y is the gray-scale value after mapping, x is an input HDR value, min and max are lower  and  upper
       bounds of the dynamic range window.

REPRODUCING MAPPING WITH PFSGAMMA

       To  reproduce  the displayed image and save it to LDR image using pfs commands, you can use the following
       commands:

       pfsin image.hdr | pfsgamma -g 2.2 -m 0.01 | pfsout image.png

       where "2.2" is the gamma value from the "Mapping" combo box, and 0.01 is the exposure value. The exposure
       is shown as the right-most number in the window status bar of pfsview.

OPTIONS

       --window_min <log_lum>

              Lower bound of the values that should be displayed or minimum value of the dynamic  range  window.
              The  value  should  be  given  in  log_10  units,  for example -1 if the lower bound should be 0.1
              (10^-1).

       --window_max <log_lum>
              Upper bound of the values that should be displayed or minimum value of the dynamic  range  window.
              The  value  should  be  given  in  log_10  units,  for example -1 if the upper bound should be 0.1
              (10^-1).

EXAMPLES

       pfsin memorial.hdr | pfsview
              See the memorial image.

       pfsv memorial.hdr
              The same as above, but using the utility script 'pv'.

SEE ALSO

       pfsv(1) pfsin(1)

BUGS

       Zomming in may sometimes show artifacts.

       Please report bugs and comments to Rafal Mantiuk <mantiuk@mpi-sb.mpg.de>.

                                                                                                      pfsview(1)