Special K

I get asked about picture quality in a video production along with the inquiry, what does K mean, as in 4K? . K = 1,000. So, 4K means 4,000. A quick history. Your old VCR recorded and played back in Standard Definition that was 720 X 480 (720 pixels across and 480 pixels tall). That's why when you watch an old VCR tape the picture looks blurry. At that pixel rate, the picture has a limited amount of information. The more pixels there are in an image, the clearer it will be. Think of it as a gallon bucket filled with liquid. It didn't bother us much back then because we had nothing to compare it to. The next step was a higher definition picture which was 1080 X 720. Now our bucket can hold more than a gallon. However today, 1920 X 1080 is generally what we refer to as High Definition (sometimes called 2K even though it actually not quite 2K).

Currently consumer and professional cameras can record and playback at 4K (OK, 4K isn't really 4k, its 3840 X 2160) also known as Ultra High Definition. Our gallon bucket is now a two gallon bucket. Some professional cameras can record 6K, 12K or even higher. YouTube and other streaming sites usually stream at HD (1920 X 1080) although we are beginning to see more Ultra HD streams.

So if you are having a video produced for you business or organization, what does it matter if it's only shot in HD? After all, most viewers will view the final edit in HD. What non-professionals don't understand is the higher quality the footage is recorded in, the image will look better, even it downsized to HD after it is edited. I call this "the heat" of the signal. The hotter the signal, the more information will be passed on even to a lesser quality render. The other advantage is being able to crop into the picture during editing (to a point) without degrading the signal to less than HD. Let me try to explain this. You have 4K footage of a boy in front of a spreading elm try. The shot was taken wide so that the entire tree can be seen. While editing it is decided that you don't need that wide of a shot. The boy is what is important in the footage. Because the footage was shot in 4K the picture can be zoomed in so the boy take up more of the frame This zoom can be to almost half the original size and still will retain a HD quality picture. This explanation is a bit simplified but basically true.

When you decide to have a video produced be sure to shoot the footage in at least 4K. Not only will the HD version look better but you have future proofed your edit as someday 4K will take over HD as the prevalent streaming format.

Thom Baker

Cinematographer and Editor at Baker Digital and former adjunct professor of Audio- Video Editing at the College of Engineering, University of Missouri.