Over the last few years even the casual film fan has had to learn the difference between native 3D and the post-converted sort; between 24fps and 48fps. But what exactly is 4K when it’s at home and why do you need it? Here’s a quick primer…
What is a 4K?
The 4K simply refers to a horizontal digital resolution of 4,000 pixels. You’ve probably seen TVs advertised as being “720p” or “1080p”, or had to faff about with your 1280X1024 computer screen / computer images / online video sizes, so you already have an idea what those are. Well, 4k comes in at almost double the width of current ‘full HD’ content and provides four times as much detail.
Why is that good?
Well, the clearer, the better – especially for audio-visual nerds like James Cameron (we mean that in the most flattering way possible). The more information in the frame, the greater the illusion of reality, so goes the thinking, and someone like Cameron creating somewhere like Pandora is all about creating an immersive reality. Even if you reduce something shot in 4K to the currently-standard 2K format, you still get more detail and clarity.
Don’t patronise me; exactly how many pixels are we talking about?
Alright, nerd! 720p video is 1280 x 720 pixels and a 1080p is 1920 x 1080 pixels. The precise size of 4K images depends on the format; “4K Ultra HD” refers to 3840 pixels x 2160 lines, and that’s what comes as standard in most of the generation of “ultra high-definition” TVs you’re beginning to see around your local electronics shops (“ultra-wide” TVs may be 5120 x 2160). In 4K cinema, however, the standard is 4096 pixels × 2160 lines, so that’s what we’d expect Cameron to use.
What’s the downside?
The problem is the sheer size and quality of the image, especially for home viewing; if you want to stream 4K content from Netflix or Amazon you could run into broadband fair use limits pretty darn quick. A single episode of House Of Cards in 4K would take 18.8GB at current compression rates – though if using the newer H265 encoding method (on devices that support it) that could go down. It’s still going to be hefty, however.*
These pixels – square or rectangular?
Wow, you know your stuff! If it’s to Rec.2020 standards, they will definitely be square.
Is this it? If I get a 4K TV and go to see Avatar 2, am I done?
Dear me, no! 8K TVs already previewed at last year’s CES, so expect the industry to move towards that format in the next few years. Still, given that 4K originally premiered in 2003, you should have a good decade before 8K becomes popular enough to trouble your broadband connection.