4K resolution
As noted above, DCI 4K is 40962160, while 4K UHD is 38402160, producing a slight difference in aspect ratio rather than a significant difference in resolution. Traditional displays, such as LCD or OLED, are 3840 pixels across the screen, with each pixel being 1/3840th of the screen width. They do not overlap—if they did, they would suffer reduced detail. The diameter of each pixel is basically 1/3840th of the screen width or 1/2160th of the screen height - either gives the same size pixel. That 38402160 works out to 8.3 megapixels, the official resolution of 4K UHD (and therefore Blu-ray UHD discs).
DirecTV
In November 2014, DirecTV became the first television provider to begin offering 4K ultra-high definition content. On launch, 4K content was limited to renting a small library of on-demand films, downloaded to the subscriber's Genie DVR (some 4K content can also be pre-loaded automatically to the set-top box via the Genie Recommends feature). The 4K service could also only be used on "DirecTV 4K Ready" televisions, which support RVU protocol; this was limited to selected Samsung 4K televisions released in 2014.