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Ask HN: Do OLED displays only save energy with absolute black?

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Ask HN: Do OLED displays only save energy with absolute black?

#1
It was always my understanding that OLED displays use less energy the darker the screen is. However I now came across some information that this is actually only true for absolute black (#000000).

Is that correct? Does #010101 use the same energy as #FFFFFF or do darker shades still use less energy?

Re: Ask HN: Do OLED displays only save energy with absolute black?

#2
(Warning: I am not a display technology expert)

I'm guessing it's a combination of yes and no. OLED screens save power on black colors because it can completely shut off the pixels responsible for illuminating that portion of the screen. If you have a slightly brighter color than pure black, the diode will turn on but not at full-brightness.

Technically speaking, you probably stand to save the most power on a purely black background. You're still saving power on other dark colors, but it's probably more noticeable with pure black.

Re: Ask HN: Do OLED displays only save energy with absolute black?

#3
post #2

(Warning: I am not a display technology expert) I'm guessing it's a combination of yes and no. OLED screens save power on black colors because it can completely shut off the pixels responsible for illuminating that portion of the screen. If you have a slightly brighter color than pure black, the diode will turn on but not at full-brightness. Technically speaking, you probably stand to save the most power on a purely…

Thanks, that's exactly what I am wondering

Is #010101 effectively #FFFFFF or does it actually use less energy the darker it is? With LCDs we know it is the former, but what about OLED displays?

Re: Ask HN: Do OLED displays only save energy with absolute black?

#4
post #3
post #2

(Warning: I am not a display technology expert) I'm guessing it's a combination of yes and no. OLED screens save power on black colors because it can completely shut off the pixels responsible for illuminating that portion of the screen. If you have a slightly brighter color than pure black, the diode will turn on but not at full-brightness. Technically speaking, you probably stand to save the most power on a purely…

Thanks, that's exactly what I am wondering Is #010101 effectively #FFFFFF or does it actually use less energy the darker it is? With LCDs we know it is the former, but what about OLED displays?

[deleted]

Re: Ask HN: Do OLED displays only save energy with absolute black?

#5
post #3
post #2

(Warning: I am not a display technology expert) I'm guessing it's a combination of yes and no. OLED screens save power on black colors because it can completely shut off the pixels responsible for illuminating that portion of the screen. If you have a slightly brighter color than pure black, the diode will turn on but not at full-brightness. Technically speaking, you probably stand to save the most power on a purely…

Thanks, that's exactly what I am wondering Is #010101 effectively #FFFFFF or does it actually use less energy the darker it is? With LCDs we know it is the former, but what about OLED displays?

I'm not sure. Considering what I know about OLED, I'd assume that #010101 consumes considerably more energy than #000000 since it needs to emit light for that individual diode. The energy efficiency from there will mostly depend on the brightness/size of the display.

Re: Ask HN: Do OLED displays only save energy with absolute black?

#6
post #3
post #2

(Warning: I am not a display technology expert) I'm guessing it's a combination of yes and no. OLED screens save power on black colors because it can completely shut off the pixels responsible for illuminating that portion of the screen. If you have a slightly brighter color than pure black, the diode will turn on but not at full-brightness. Technically speaking, you probably stand to save the most power on a purely…

Thanks, that's exactly what I am wondering Is #010101 effectively #FFFFFF or does it actually use less energy the darker it is? With LCDs we know it is the former, but what about OLED displays?

The brighter the pixels are, the more power they are using. A pixel uses 0 power at 0 brightness, and it goes up from there.

Re: Ask HN: Do OLED displays only save energy with absolute black?

#7
post #2

(Warning: I am not a display technology expert) I'm guessing it's a combination of yes and no. OLED screens save power on black colors because it can completely shut off the pixels responsible for illuminating that portion of the screen. If you have a slightly brighter color than pure black, the diode will turn on but not at full-brightness. Technically speaking, you probably stand to save the most power on a purely…

I found the following research paper that does seem to support your educated guess:

Energy Aware Color Sets

https://eprints.cs.univie.ac.at/4187/1/eg09_color.pdf

Re: Ask HN: Do OLED displays only save energy with absolute black?

#9
The engineering answer is to test and measure the actual hardware that is being considered because implementations often vary from theory in significant ways due to the quality of components, the competence of the design team, the design priority of energy saving, the design budget, the generation of technology, and other factors that abide in meat-space.

I mean the display panel A might be 20% more efficient than display panel B, but connected to a power supply that is half as efficient as B's.

Good luck.

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