4K resolution
This resolution is used mainly in digital cinema production, and has a total of 8,847,360 pixels with an aspect ratio 256135 (≈1910). It was standardized as the resolution of the 4K container format defined by Digital Cinema Initiatives in the Digital Cinema System Specification, and is the native resolution of all DCI-compliant 4K digital projectors and monitors. The DCI specification allows several different resolutions for the content inside the container, depending on the desired aspect ratio. The allowed resolutions are defined in SMPTE 428-1: The DCI 4K standard has twice the horizontal and vertical resolution of DCI 2K (), with four times as many pixels overall.
Home cinema
By the mid-2010s, the Blu-ray Disc medium had become a common home media standard, and online video streaming sources such as Netflix and YouTube were offering a range of high definition content, including some 4K content (although various compression technologies are applied to make this streamed content feasible). The first 4K Blu-ray discs were released in 2016. By this point, 4K TVs and computer monitors were rapidly declining in price and increasing in prevalence, despite a lack of native 4K content. While many DSP systems existed, DTS-HD Master Audio remained the studio standard for lossless surround sound encoding on Blu-ray, with five or seven native discrete channels. High definition video projectors also continued to improve and decrease in price, relative to performance.