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)