gamma4scanimage(1)       SANE Scanner Access Now Easy       gamma4scanimage(1)


       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 being 1.0. If the  value
       is larger than 1.0 then the image is 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 must be in  the  range  [0..maxin]  and
       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 bit gamma input then maxin must
       be set to 255, 1023 for 10 bits, 4095 for 12 bits,  and  16383  for  14
       bits.  The  default  is 16383.  To find out what value maxin has to be,
       call scanimage(1) with a very large  gamma  table  [0]0-[99999]255  and
       scanimage(1)  will  print  an error message with the needed gamma table

       maxout defines the maximum output value. Take a look at the  output  of
       scanimage -h to find out what maxout must be. The default value is 255.


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


       sane(7), scanimage(1)


       Oliver Rauch



                                  10 Jul 2008               gamma4scanimage(1)

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