4K resolution refers to a horizontal display resolution of approximately 4,000 pixels. Digital television and digital cinematography commonly use several 4K resolutions. The movie projection industry uses 4096 × 2160. In television, 3840 × 2160 with a 16:9 aspect ratio is the dominant standard. Many 4K Blu-ray releases of ultrawide films use a letterboxed form of this, keeping the horizontal resolution of 3840 pixels while the effective vertical resolution is about 1600–1620 pixels.