4K resolution talks about a horizontal display resolution of about 4,000 pixels. Digital television and digital cinematography commonly use several different 4K resolutions. In television and consumer media, 3840x2160 (4K UHD) is a common 4K standard. The movie projection industry uses 4096x2160 (DCI 4K). The 4K used for iMac's display is 4096 x 2304 px.