The campaign referenced by GP is very old. It dates from before OLEDs. LCDs were the most common screen type and CRTs second most common at the time.

How much does it draw in total before / after? Curious how much of a percentage change this is

228w - total system draw with LG C1 off/standby

270w - #000000 fullscreen

332w - #FFFFFF fullscreen

270w-228w = 42w #000000 fullscreen power draw

332w-228w = 104w #FFFFFF fullscreen power draw

( 104w - 42w ) / 42w = 2.4761

so ~248% more power usage from the screen for full #FFFFFF.

One thing to note is I have the OLED pixel brightness set to 50/100 and the brightness set to 50/100. 2.2 Gamma, black level: full. The LG C1 has some auto brightness baked into the firmware and it fluctuates, I tried to measure it at full brightness but as you can see today it's at 62w over #000000 compared to before so there is some deviation. However, I think it's safe to say that darker colors do actually save substantial power on OLED displays. Plus the black levels really are just amazing. Black is actually black and not a weird grayish with backlight shining through like TN/IPS LCDs.

edit: formatting.

What was the difference?

64 watts?