I started wondering about this when I realized most websites I visit have white backgrounds, and I know that the screen is usually responsible for most of the battery usage. Since I can't change the background in those sites, I might at least switch my wallpaper to a black one.

Most (all?) phones need back-lighting to brighten the screen when needed. Since that back-lighting consumes battery, **is it correct to state that a white screen consumes energy at a faster rate than a black one?** *(assuming the same brightness level in the settings)*

I'm assuming that a white screen needs stronger back-lighting, but I don't know if it's the case.
['https://android.stackexchange.com/questions/5043', 'https://android.stackexchange.com', 'https://android.stackexchange.com/users/1926/']
On OLED, AMOLED and Super AMOLED screens: [Yes](http://techlogg.com/2010/12/ips-vs-amoled-vs-slcd-smartphone-displays-explained/1877)

LCD screens: [No](http://techlogg.com/2010/05/black-vs-white-screen-power-consumption-24-more-monitors-tested/17)
This depends on the screen technology. 

For instance, (it was said that) Android 2.3 Gingerbread has dark theme since Google's latest flagship device Nexus S uses (Super) AMOLED display which consumes less energy when displaying dark color since AMOLED produces its own light and darker color emits less photons. Contrasts with LCD display which uses a backlight (a fixed number of photons) and the LCD crystals filters those colors it needs. The crystals on an LCD displays though, actually consume slightly less power when displaying white since it takes more power to strain the crystal to block more light.

Screen color does not affect the backlighting. There are certain display technologies in TVs that tries to give dynamic backlighting by dimming the screen when displaying darker image. I'm not aware of any device that actually ships with that type of screen though.