4K UHD

4K UHD is a 3840×2160 image format used in consumer televisions and video distribution. It has an aspect ratio of 16:9 and a total of approximately 8.29 million pixels, which is four times that of 1920×1080. ITU-R BT.2020 defines 3840×2160 and 7680×4320 as two tiers of Ultra High Definition (UHD) television image systems. Television 4K UHD differs from digital cinema 4K. Digital cinema commonly uses DCI 4096×2160, which features a wider aspect ratio and operates under a different set of requirements for container formats, color, and frame rates. In product marketing, “4K” is sometimes used generically to refer to a resolution with approximately 4,000 horizontal pixels; databases should prioritize recording the actual resolution.

4K does not automatically imply HDR.

The 3840×2160 resolution can utilize different dynamic ranges—such as SDR, HDR10, HLG, and Dolby Vision—and may also employ different color gamuts, bit depths, frame rates, and encoding methods. Ultra HD Blu-ray typically combines HEVC, 10-bit, and HDR, but the specifications also allow for SDR; online 4K content may have different compression rates and chroma subsampling. “4K restoration,” “4K scan,” “4K digital intermediate,” and 4K release describe different stages of the process. Film scanned at 4K may be released only in 1080p, and 4K discs may originate from 2K intermediate material or upscaled masters. The final pixel size specifies the delivery format but does not, by itself, prove that the source material has an equivalent effective resolution.