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I have read on web, for CRTs black color would reduce the power consumption of the monitor but for LCDs it's the white color that reduce the power consumption.

It says "The way LCD's produce black is to energize all the pixels that need to be black".

But this website says no matter its CRT or LCD, using darker colors reduce the power consumption.

So which one is correct? Will using black backgrounds will save my laptop battery? I know anyway darker backgrounds are easier for my eyes.

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Conventional LCDs and LED based LCDs consume power that largely depends only on the intensity of backlight. This means to save power you want to reduce brightness of the screen.

OLED displays, like those found in Samsung (and other) smartphones, on the other hand, have power consumption that depends on color being displayed. If i remember correctly, it was something like Red<Blue<Green, but that order would be device dependant, I remember that some smartphone had it as R<G<B. Basically in such situations, white is your enemy, search for apps that have night mode, since black color consumes minimum(not 0) power.

However, to answer your question, since AFAIK OLEDs havent gone mainstream beyond phones as of yet, Darker backgrounds will not save power, but darker display over all (Reduce brightness) will.

Edit: Dynamic Brightness, as mentioned by @Bob, might be used in LED based LCDs which might reduce power based on darkness of color.

A way to test this is to display a black screen in a dark room and see how close to black it actually is. Typically it would be very bright since the backlight is still blazing away even if the LCD tries to block most of that light.

  • FYI, an update (mid 2019) more modern LED LCDs that use "local dimming" to reduce the brightness of the backlights in small localized regions if most of that area of the screen is to display darker content. So dark mode on these LED LCD monitors will save power due to more dimming. However, using a high contrast, dark writing on light background (that matches ambient room lighting) is normally easier on your eyes. Still turn the brightness down to save power. – BeowulfNode42 Jun 26 at 4:39
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To my knowledge, the fact that the backlight is always on means that the color of the pixels will not affect power consumption. That's why backlight brightness is the factor. Some newer screens (like OLED) are different and with those you could actually save battery with a darker background.

  • Except TN LCD screens (I'm not sure about IPS) require (a negligible amount of) power to block the blacklight in certain areas, making it appear dark/black. Some smarter LED based LCD screens may even dim the LEDs in certain areas, conserving power. – Bob Nov 1 '12 at 8:50
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Not true, most of todays LCD's consume more power for Black screens as the backlight remains at same power but pixel drivers need to fire. This was tested on Dell 2408WFP and Samsung SyncMaster B2230W. The monitor tested on the pcSTATS site is an antique and probably had some sort of adaptive backlight brightness.

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