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 default value
is 255.
scanimage --custom-gamma=yes --gamma-table `gamma4scanimage 1.8 0 11500 16383
255` >image.pnm
sane(7),
scanimage(1)
Oliver Rauch
[email protected]