4K = 1080P x 2?

[ArnoldRimmer]

Galaki said:

Wait. I thought 4K means 4 times the resolution of 1080P?

That's exactly what the picture states.

4K has twice the resolution in both directions (1920*2=3840, 1080*2=2160), so it has 4 times the number of pixels and thus 4 times the resolution overall.