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
High-resolution displays such as 8K allow for each pixel to be indistinguishable to the human eye when viewed at a typical distance from the screen. 8K resolution can also be used for the purpose of creating enhanced lower resolution videos through a combination of cropping techniques and/or with downsampling techniques used in video and film editing. Resolutions such as 8K allows filmmakers to shoot in a high resolution with a wide lens or at a further distance, in the case of potentially dangerous subjects (such as in wildlife documentaries), by being able to zoom and crop digitally in post-production. The technique involves taking a portion of the original 8K image and cropping it to match a smaller resolution such as the current industry standard for high-definition televisions (4K, 1080p, and 720p).