I’ve seen this bandied about for the longest time and never really thought much of it until it came up again today in the description for an iPhone app, so now I’ve just gotta ask.
Does setting a black background on an LCD screen really conserve battery life?
I’m tempted to call shenanigans here because of two rather important factors:
Sending a signal for “black” to the screen still requires that the pixels be turned on just as they would be for any other colour. They’re just sent whatever the amount of current is needed for black.
Black doesn’t turn off parts of the backlighting – it just blocks the light from getting through. Since the backlight is usually the biggest drain on power, setting a black screen would have zero effect here.
The only reason I can think of that setting a black background could conserve power is that maybe the amount current required to twist the crystals to black is less than that required for any other colour – but in such a case, surely the reduced power consumption must be so minor as to be almost meaningless, no?
Anyone know the straight dope?