4K resolution
So while 4K UHD sounds like it has a pixel structures with 1/4 the area of 1080p, that does not happen with pixel shifting. Only a true 4K projector offers that level of resolution. That's why "true" 4K projectors cost so much more than 4K UHD projectors with otherwise similar feature sets. They produce smaller pixels, finer resolution, no compromising of detail or color from overlapping pixels. By comparison, the slight difference in aspect ratio between DCI and 3840×2160 pixel displays without overlap is insignificant relative to the amount of detail.
Graphics display resolution
This resolution, sometimes referred to as 4K UHD or 4K2K, has a 16:9 aspect ratio and 8,294,400 pixels. It is double the size of Full HD (19201080) in both dimensions for a total of four times as many pixels, and triple the size of HD (1280720) in both dimensions for a total of nine times as many pixels. 38402160 was chosen as the resolution of the UHDTV1 format defined in SMPTE ST 2036-1, as well as the 4K UHDTV system defined in ITU-R BT.2020 and the UHD-1 broadcast standard from DVB. It is also the minimum resolution requirement for CEA's definition of an "Ultra HD" display. Prior to the publication of these standards, it was sometimes casually referred to as "QFHD" (Quad Full HD).