gamma4scanimage.1

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

NAME

       gamma4scanimage - create a gamma table for scanimage

SYNOPSIS

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

DESCRIPTION

       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 default value is 255.

EXAMPLE

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

SEE ALSO

       sane(7), scanimage(1)

AUTHOR

       Oliver Rauch

EMAIL-CONTACT

       Oliver.Rauch@Rauch-Domain.DE

                                  10 Jul 2008               gamma4scanimage(1)