I'm wondering what color-scheme is more energy-saving for AMOLED display?
I've already decided to manage c-scheme according to ambient light, thanks to this post:
Somewhat-proof, the link posted by nickf: Ironic Sans: Ow My Eyes. If you read that in a well lit room, the black-on-white will be the most pleasant to read. If you read it in a dark room, the white-on-black will be nicer.
But if I want to save battery power, should I use bright content with dark background or vice versa?
Is it possible anyway (they say it's not working for simple LCD)?
Yes, you can. The best you can do is use a red on black color scheme. Blue is more expensive than green, green more than red. White is the worst :)
To give you an idea, a static blue wallpaper (for instance a jellyfish in an aquarium) consumes more battery than the 3D galaxy live wallpaper.