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 size.

       maxout  defines the maximum output value. Take a look at the output of scanimage -h to find out what maxout must be. The de‐
       fault 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)