xenial (1) pfsdisplayfunction.1.gz

NAME

       pfsdisplayfunction - Apply display function to color or gray-scale images

SYNOPSIS

       pfsdisplayfunction [--display-function <df-spec>] [--to-pixels | --to-luminance] [--help] [--verbose]

DESCRIPTION

       Use  this  command  to  convert  pixel  values to luminance / radiance units displayed on a monitor or to
       perform inverse conversion. This command is useful in combination with the HDR-VDP to convert LDR  images
       to  luminance  maps representing images shown on a particular display. The display function specification
       is identical to the specification used in the pfstmo_mantiuk08 tone mapping  operator  (from  the  pfstmo
       package).

       If  neither --to-luminance nor --to-pixels option is specified, the appropriate conversion direction will
       be deducted from the LUMINANCE tag in the pfs stream.

OPTIONS

       --to-luminance, -l
              Convert pixel values to absolute luminance / radiance units.  For  RGB  images  the  same  display
              function is applied in each color channel.

       --to-pixels, -p
              Convert  absolute  luminance  /  radiance  units  to pixel values. For RGB images the same display
              function is applied in each color channel.

       --display-function <df-spec>, -d <df-spec>
              The display function describes how output luminance of a display changes with pixel values. If  no
              parameter  is  given,  the  command  assumes -df pd=lcd (see Pre-defined display below). There are
              several ways to specify the display function:

       Gamma-gain-black-ambient display model

              g=<float>:l=<float>:b=<float>:k=<float>:a=<float>[:n=<float>]

              Gamma-gain-black-ambient model can approximate a range of displays and is a compact way to specify
              a display function. It assumes that a display function has the following form:

              L_d(I) = (l-b)*I^gamma + b + k/pi*a

              The parameters are as follows:
              g -  gamma or exponent of a display function (default 2.2, usually from 1.8 to 2.8)
              l -  peak  luminance  of  a  display  in cd/m^2  (default 100, from 80 for CRTs to 500 or more for
                   newer displays)
              b -  black level, which is luminance of a black pixel when the display is on (default  1,  usually
                   from 0.3 to 1 cd/m^2)
              k -  reflectivity of a screen (assuming that it is diffuse) (default 0.01, usually about 0.01 (1%)
                   for LCD displays, more for CRTs)
              a -  ambient illumination in lux. Typical values are:
                   50 lux Family living room (dim, default)
                   400 lux
                          A brightly lit office
                   32000 lux
                          Sunlight on an average day (min.)
                   100000 lux
                          Sunlight on an average day (max.)

       Pre-defined display

              pd=<display_type>

              Use pre-defined display type. This options are for convenience  only  and  they  do  not  mean  to
              accurately  model  the  response  of  a  particular  display.   The  following  display  types are
              recognized:

              lcd_office (g=2.2, l=100, b=0.8, k=0.01, a=400 )
                     lcd set to "office" mode seen in bright environment
              lcd        (g=2.2, l=200, b=0.8, k=0.01, a=60  )
                     typical lcd seen in dim environment (default)
              lcd_bright (g=2.6, l=500, b=0.5, k=0.01, a=10  )
                     newer LCD TV seen in dark environment
              crt        (g=2.2, l=80,  b=1,   k=0.02, a=60  )
                     CRT monitor seen in dim environment

              The parameters in the parenthesis are the same as for the gamma-gain-black-ambient model explained
              above.

       Lookup-table

              lut=<file>

              This  is  the most accurate specification of the display response function, but requires measuring
              it with a luminance meter. The lookup table should account also for ambient light, so that  it  is
              recommended  to use the luminance meter that can measure screen luminance from a distance, such as
              Minolta LS-100 (as opposed to those that use rubber tube touching a display  that  eliminates  the
              influence of ambient light). The <file> must be a comma-separated text file in a format (CSV) with
              two columns: first column represents pixel values (from  0.0  to  1.0)  and  the  second  physical
              luminance in cd/m^2. Both the pixel value and the luminance should increase in each raw.

EXAMPLES

       pfsin barbara.jpg | pfsdisplayfunction -l -d pd:crt -v  | pfsout barbara_crt.hdr

              Convert barbara.jpg image from pixel values to a luminance map of the image shown on a CRT monitor
              and store the map as an HDR image.

SEE ALSO

       pfsgamma(1) pfstmo_mantiuk08(1)

BUGS

       Please     report     bugs     and     comments      to      the      pfstools      discussion      group
       (http://groups.google.com/group/pfstools).

                                                                                           pfsdisplayfunction(1)