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.
8K resolution
, few cameras had the capability to shoot video in 8K, with NHK being one of the only companies to have created a small broadcasting camera with an 8K image sensor. By 2018 Red Digital Cinema Camera Company had delivered three 8K cameras in both a Full Frame sensor and Super 35 sensor. Until major content sources are available, 8K is speculated to become a mainstream consumer display resolution around 2023 as mentioned in UHD forum Phase-B recommendations. Despite this, 
filmmakers are pushing demand for 8K cameras due to their ability to capture better 4K footage.