Now that there’s an iPhone that can shoot 4K video—yes, yes, Android users, we see that face you’re making—we thought it was time to put together a nice, simple guide to 4K video, explaining what it is, what it means, and how—and when—to use it.
The basics: What is 4K?
Firstly, the “4K” that 4K refers to is the number of pixels across a video file’s horizontal dimension—which is around 4000. (Note that HD resolutions usually refer to the vertical dimension, just to keep you on your toes.) HD video, the previous standard, came in a few specific versions, but today most of us would understand it to mean 1080p, that is, a video resolution of 1920-by-1080 pixels. Compare those two horizontal measurements, 1920 and “around 4000,” and you’ll note that 4K video has more pixels. That is, all things being equal, 4K video contains more detail than HD video, in a similar way to how a Blu-ray’s image has more detail than a DVD’s, and so images look sharper and more lifelike. (There are lots of technical details about codecs and color spaces and frame-rate that can get in the way here, but let’s not get bogged down.)
Read more here:: How and when to capture 4K video on the iPhone 6s and 6s Plus