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 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 table.

       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 255.

EXAMPLE

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

SEE ALSO

       scanimage(1)

AUTHOR

       Oliver Rauch

EMAIL-CONTACT

       Oliver.Rauch@Rauch-Domain.DE

                                           10 Jul 2008                         gamma4scanimage(1)