gamma4scanimage - create a gamma table for scanimage


   gamma4scanimage gamma [shadow [highlight [maxin [maxout]]]]


   The  tool  gamma4scanimage creates a gamma table in the format expected
   by scanimage. You can define a gamma, a shadow and a  highlight  value.
   You also can specify the size (maxin) and maximum output value (maxout)
   of the gamma table.

   gamma is a floating point value, neutral value is 1.0, if the value  is
   larger than 1.0 then the image gets brighter.

   shadow  defines  the minimum input value that is necessary to create an
   output value  larger  than  zero.   shadow  has  to  be  in  the  range
   [0..maxin]. Its default value is 0.

   highlight defines the maximum input value that produces an output value
   smaller than maxout.  highlight has to  be  in  the  range  [0..maxin],
   highlight  has  to be larger than shadow. Its default value is the same
   as maxin (16383 if not set).

   maxin defines the size of the gamma table.  The  size  depends  on  the
   scanner/backend.  If the scanner uses 8 bits gamma input then maxin has
   to be set to 255, for 10 bits 1023, for  12  bits  4095,  for  14  bits
   16383.  The  default  is 16383.  To find out what value maxin has to be
   call scanimage with a  very  large  gamma  table  [0]0-[99999]255  then
   scanimage  prints  an  error  message with the needed size of the gamma

   maxout defines the maximum output value. Take a look at the  output  of
   scanimage  -h  to  find out what maxout has to be. The default value is


   scanimage --custom-gamma=yes --gamma-table `gamma4scanimage 1.8 0 11500
   16383 255` >image.pnm




   Oliver Rauch



                              10 Jul 2008               gamma4scanimage(1)


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