[sane-devel] Contrast an gamma

[Gerhard Strangar]

Hello,

I don't know if I just fail to see how it works or if it just doesn't. I
have a scanner that wirks fine via the pixma backend and while scanimage
does allow changing the brightness, I'd like to change the contrast. I'm
sure, I used --contrast some years ago with a different backend, but I
don't know if it was backend-specific.
Then I thought it might be worth trying to just do some gamma correction
if I cannot change the contrast. But all I get is purge black.
Apparently the scanner uses 10 bits, so shouldn't "gamma4scanimage 1.0 0
1 1023 255" get me an all-white image and "gamma4scanimage 1.0 0 1023
1023 255" make no change at all?

pixma:04A91913_549FD0
scanimage (sane-backends) 1.4.0; backend version 1.4.0

I will just pipe it through Imagemagick. I'm just wondering why
scnaimage does have a brightness option, but no contrast and if I
misunderstood the gamma option or if it doesn't work.

Gerhard