For people that work with video everyday the phrase 4k is fairly common. Others however may not come across it all that often or have been explained what it is or why it is used?
What is 4k?
These days we consider HD (High Definition) video to be a standard. This is not always the case with footage shot on phones or other devices but it is the most commonly used resolution.
HD is 1920 x 1080. This means that when you watch HD footage you are seeing a screen with 2,073,600 pixels (1920 pixels wide and 1080 pixels high). Essentially for every 16 pixels of width you have 9 pixels of height. Hence the ratio 16:9 used to describe the shape of this footage.
4k or Ultra High Definition (UHD) is any resolution that has about 4000 pixels on either its width or height.
For the purpose of television, online video and most content this means doubling HD (3840 x 2160), which keeps the ratio of 16:9.
For films this means a slightly different size of 4096 x 2160
What does it do?
The easy answer to this is – “It makes the quality of the image better”.
More pixels mean that you can see more detail which allows for a sharper, more defined image.
In real terms however the eye is only capable of seeing so much detail from a set distance. What this means is that in order to appreciate the detail of your 4k screen or display you need to be closer to it. If you are further away you won’t see an appreciable difference between it and HD.
Pros and cons of watching 4k
4k, especially if you are close enough to appreciate it, is a truly beautiful image.
This quality comes at a cost.
The file size is much larger. On broadcast TVs this won’t be an issue (if and when we regularly get 4k content broadcast) but for anything streamed online, YouTube, Netflix, your website etc. it means longer wait times whilst the content downloads (buffers).
Pros and cons of filming 4k
Filming in 4k is a slightly more complicated issue. If the end product needs to be in 4k obviously you should be shooting in 4k.
The compromise here is again the file size. 4k files can be more than twice the size of regular HD. This means you need much more storage (hard drive space) for the files and you need a faster computer (processor, graphics and RAM) to be able to edit 4k files with any practical speed. There are ways around this e.g. proxies but that is a whole different issue.
If you are delivering a video in a resolution smaller than 4k there is one extra big advantage. You are able to crop and zoom in on 4k footage without losing the quality of an image. This means that you can change the shot after the cameras have finished rolling.
Should you be using 4k?
4k is currently not necessary for most use cases. It does have its advantages and you should discuss these with clients on a project by project basis. Most professional cameras give you the option to shoot in 4k so as long as you plan for additional edit time and storage space it is entirely do-able.
Regardless of what resolution you use… you should still be focussing on good quality content that suits the audience you are targeting.
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