The terms 2K, 4K, or 8K standard come from the Digital Cinema Initiative( DCI) and stand for a graphic resolution ofdigital TV and digital cinematography. The numerical value refers to the horizontal resolution, although this value may show slight differences depending on the display format.
For the 4K standard, the horizontal resolution is equivalent to Ultra High Definition( UHD), with 3,840 pixels, and the vertical pixel count is 2,160. The aspect ratio is 16:9, and this resolution is also referred to as UHD-1.
There are other 4k (small k) formats from the Digital Cinema Initiative (DCI) for D-Cinema with 3,996 or 4,096 horizontal pixels. Accordingly, the possible aspect ratios also vary between 1.85:1, 1.90:1 and 1.78:1 and the vertical resolutions between 2,160 pixels for 4K HDMI and 2,304 for 4k Cinema.
The 4K format has twice the horizontal resolution of the 2K format and half that of the 8K standard. In terms of pixel count, the 4K format has four times the pixel count of the 2K format, and 8K has 4 times the pixel count of the 4K standard and 16 times the pixel count of the 2K standard. In numbers, the 2K representation is about 2.2 megapixels( MP), the 4K representation is about 8.85 MP and 9.44 MP, respectively, and the 8K representation is 34 MP.
The next largest image format above 4K is the 5K standard at 5,120 x 2,880 pixels.