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# 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 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 scan‐
           image 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)