Four Things You Need to Know About 4K in 2021

The first major home theater buzzword of the new millennium was HD. Then came 3D, and now it's 4K. But what is 4K really all about, and how does it relate to past and future technology? Here are four facts about 4K in 2021.

The term 4K, or four thousand, was initially an industry term used to refer to the diagonal resolution of a cinematic video standard with the vertical pixel count of 2160p. The lower standard with a vertical pixel count of 1080p is called 2K. While both have the same vertical resolution as consumer televisions, their horizontal resolution is larger, and to adapt to home media the video's resolution is either lowered and letterboxed or the excess is cropped off. In marketing, the term 4K which refers to the larger cinematic standard was thrown around a lot, and while it isn't technically accurate, it stuck and is now widely accepted.

If there's one thing that might be surprising, it's that much of the content made today isn't 4K at all, but is 1080p. Many movies that are released on the new 4K Blu-ray standard are actually upscaled and not 2160p at all. Why? One of the main answers would be the limits of computing power. As a matter of fact, not one animated film has been mastered in 4K. The same goes for most CGI work in movies that are otherwise 4K. Even many live action movies with few special effects have been mastered in 2K and upscaled for 4K home media. While many films have been recorded in 4K or even higher resolutions for years, even before it was a television standard, the purpose was for post production. For instance, shots could be cropped, zoomed in or moved around while retaining full clarity when finalized in 2K. Only recently was it considered to render the final product in 4K. Once an edited film is finalized in 2K however, it's uneconomical or downright impossible to re-render it at a higher resolution. So even if you may see information stating that a given film was recorded in a resolution higher than 2K, the only number that matters in the end is the resolution it was finished at, and some websites are devoted to archiving such information.

Does this mean that 4K Blu-ray is a scam whenever it contains movies not natively mastered that way? No, because there's more to the 4K standard that resolution alone. For this reason the new Blu-ray disc standard is officially called Ultra-HD Blu-ray to draw attention to the overall benefits besides resolution. One upgrade would be HDR, or high dynamic range. This gives not only brighter brights and deeper, more detailed blacks but also a larger range of colors for more vivid, lifelike imagery. Utilizing a 4K rendering of native 2K content, especially in the case of 4K streaming services, also leads to a cleaner overall picture without the plague of compression artifacts that frequent standard HD streams. Another potential benefit is HFR, or high frame rate. While movies are generally filmed at 24 frames per second, and many TV shows at 30, Ultra-HD Blu-ray allows up to 60 frames per second resulting in amazing fluidity of movement and elimination of judder that often plagues horizontal movement in films. While many consumer phones, cameras and camcorders have the option of recording in this format, only a handful of Hollywood movies have been made that way and out of them only two have been released on Ultra-HD Blu-ray.

As mentioned before, while a number of current films aren't made in 4K they still benefit from the new standards for HDR, or high dynamic range. Many 3D movies have been made and released this way theatrically, including all the new Star Wars movies, most animated films and others. Thus it came as a surprise to many when the new Ultra-HD Blu-ray standard was announced and it was said that 3D would not be supported. While some Blu-ray combo packs include both 3D and 4K HDR discs, customers have to choose between them and don't have the option of watching a film in its original format. What many don't realize is that the current Ultra-HD Blu-ray standard is already capable of playing Ultra-HD, HDR and 3D at the same time. This has already been done with the world's first 4K 3D Ultra-HD Blu-ray, available here, but has yet to be done with Hollywood films outside of premium theaters. Hopefully both 3D and HFR will be used in the future, because they are much more of a noticable upgrade than the resolution, and all the more so together. Until then, Ultra-HD Blu-ray will be greatly underutilized. Thankfully though, great new projectors continue to be produced that feature all current standards of 4K, 3D and HDR, such as this recent model among others.