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 scan-
ner/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 scanim-
age(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)
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