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.
Vudu
Movies are encoded in MPEG-4 video and Dolby Digital Plus audio. Vudu offers movies in three formats: standard-definition (480p and 480i), high-definition (1080p and 1080i) and ultra high-definition (2160p) or commonly known as UHD or 4k. Standard-definition movies are up-scaled to higher 1080i/p resolution and high-definition movies can be output at 1080p24. Audio is sourced in Dolby Digital Plus and output in Dolby Digital 5.1, with the option of stereo output. Audio is limited to stereo playback on HTPC/PC/Mac platforms. Users are able to adjust video to display in stretched, boxed, or zoomed format as well as adjusting overscan settings depending on their television format.