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
Oliver.Rauch@Rauch-Domain.DE