If you don't see brightness or gamma in the Options menu, those controls are not there. Syberia 3 seems to be very deficient in options compared to most current 3D games. I've seen other complaints about the game being too dark or too murky.
This is someone's Syberia 3 tweak, announced at Steam. http://steamcommunity.com/sharedfiles/filedetails/?id=913309310https://sfx.thelazy.net/games/preset/7157/
I don't know anything about it other than what's posted. The comments say it's an improvement.
Apparently it's "fashionable" for modern games to have washed out, dreary, colorless graphics in high resolution. If you explore the sfx.thelazy.net link you can see he's made similar presets to improve the appearance of many other games.
I expect all the tweaker does is also possible through your video card settings, but quicker and easier using the tweaker.