system
Given the following post, respond as if you're commenting on Reddit:
human
Does a computer display use more energy displaying white pixels rather than black pixels?
gpt
It depends on the specific display technology and implementation.  As a general rule of thumb, if a display tech is emissive, it most likely uses more power as the picture gets brighter.  It might also be better to think of it as "using less power for the black pixels," because in general, we're comparing displays like LCDs that have an "always on" backlight to displays that don't produce light in parts of the picture that don't need it.

CRTs intrinsically use more energy showing white than black.  The power consumption is directly proportional to the light produced.

Plasma displays are similar.  Each pixel is its own light source, and they use more power when they're bright than when they're dim.

LCDs, in their most straightforward implementation, don't use noticeably more power in either direction.  The backlight is the largest power draw, and it is always on, whether individual pixels are white or black.

LCDs that implement some sort of Dynamic Contrast Ratio can use more when the picture is bright rather than dark because they adjust the backlight brightness to suit the scene.  

LCDs with local backlight dimming are more similar to something like a plasma, since the backlight can be dimmed in specific areas, reducing power use (and improving black level) where the pixels are black.

OLED displays (actual OLED, not LCDs using OLED backlights) are emissive, so they go in the list of stuff that uses more power when pixels are bright.

VFDs LED array (like stadium TVs), SED, and the like are also emissive displays with power proportional to brightness.

Reflective LCD, DLP, LCD projection, LCoS, and Laser (really just DLP with a laser light source) televisions are also technologies where the power either doesn't vary with brightness, or only does so if there is some sort of Dynamic Contrast Ratio implementation.