.TH gamma4scanimage 1 "18 august 2002"
.IX sane-umax

.SH NAME
gamma4scanimage

.SH ABOUT THIS FILE

This file gives a short information about the usage and options of gamma4scanimage

.SH DESCRIPTION

The tool
.B gamma4scanimage
creates a gamma table in the format expected by scanimage. You can define a
.BR gamma,
a
.BR shadow
and a
.BR highlight
value. You also have to specify the size (
.BR maxin
) and maximum output value (
.BR maxout
)
of the gamma table.

Usage: gamma4scanimage gamma [shadow [highlight [maxin [maxout]]]]

.BR gamma
is a floating point value, neutral value is 1.0, if the value is larger than 1.0
then the image gets brighter.

.BR shadow
defines the minmum input value that is necessary to create an output value larger than zero.
shadow has to be in the range [0..maxin].

.BR 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.

.BR 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.

.BR maxout
defines the maximum output value. Take a look at the output of scanimage -h to find out
what maxout has to be.

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

.SH SEE ALSO
scanimage(7)

.SH AUTHOR

Oliver Rauch

.SH EMAIL-CONTACT
Oliver.Rauch@Rauch-Domain.DE