After my review of the DJI Lito X1 the other day, I was asked a question in one of the DJI Forums that off the cuff I didn’t know the answer to. That question was, “Is the video format of the Lito X1 in 4:2:0 format or 4:2:2?”
As it turns out, all DJI drones *appear* to be 4:2:0, but I am awaiting official confirmation of that as some of the higher end models I don’t have access to might be 4:2:2 – eg the cinematography Inspire series.
But I suddenly thought; I wonder how many people out there would actually know what 4:2:2 and 4:2:0 means in terms of video, and how does it affect what they do, if it even does.
So here goes – and yes, it is important in certain circumstances.
4:2:2 versus 4:2:0
The difference between 4:2:0 and 4:2:2 is about chroma subsampling—how much colour information is stored relative to luminance (brightness) in a video signal. You see, video is split into two areas, and these are Luma, which is brightness and details and what you can see most, and Chroma, which is the actual colour information.
So, if a video signal is 4:2:2 it means for every 4 pixels of brightness you also get 2 colour samples horizontally and full colour vertically.
On the other hand, if the video signal is 4:2:0 for every 4 pixels of brightness you get 2 colour samples horizontally but zero colour samples vertically.
The result of using 4:2:2 therefore means you have better colour fidelity, cleaner edges and this is the preferred format for editing and broadcast. 4:2:0 in contrast is only half the resolution horizontally and has much less colour overall.
OK, that’s the technical side of it, but what does it mean in the real world?
But Does It Matter?
If shooting 4:2:0 you’ll get a slight colour smearing in fine detail such as hair, leaves and text will have blocky edges, and it is harder to colour grade.
4:2:2 on the other hand has sharper colour, better skin tones and will hold the details in such things as foliage, fabric and motion.
If you edit your footage, 4:2:2 holds up better if you do such things as increase contrast, adjust white balance or boost the saturation. You’ll definitely notice the difference between 4:2:2 and 4:2:0 if you shoot green screens (chromakeying) and use lots of text and graphic overlays.
But if your drone, camera or smartphone etc are stuck on 4:2:0, don’t despair as the average person will notice no difference on footage played back on a TV, via YouTube, Netflix or other streaming services.
If however you do colour grading of your footage, green screen work or shoot professionally, you will notice.
In my case for example, my Blackmagic Pocket Cinema Camera 6K Pro is 4:2:2 compatible and if I am shooting “serious” stuff I’ll use this, but something like the DJI Pocket 4 is not, being stuck on 4:2:0.
Bit Depth
Now, just to confuse things a little, video is also described by its bit depth. For example the DJI Lito X1 and the Pocket Camera 4 both support 10-bit colour, and this is a measure of how precise the colours are as against how much colour information there is which is what 4:2:0 and 4:2:2 describe. SDo 10-bit colour is better than 8-bit.
Log Based Video
Finally, you might also see reference to D-Log (DJI) or C-Log (Canon). When you shoot with a Log version (named differently between vendors), what you get looks like a washed out, low contrast and desaturated video. This is done on purpose, as against “normal” video which looks OK straight out of the camera.
Although log-based video looks pretty grim initially, it actually retains a lot more information in the signal for a colour grader to make it as good as it can possibly be. Needless to say, this is a specialised job and takes a LOT of practice and software that lets you grade. DaVinci Resolve is acknowledged as the top dog in this area and the reason it is used in so many major movies and TV shows for both editing and grading. (and the base version is free)
In practice, using D-Log or C-Log etc, lets the pro grader do things such as recover bright skies, lift dark shadows, change white balance and very, very importantly, match shots from different cameras.
A very simple analogy is the difference between a JPG still photo (=8 bit standard video) and a RAW still shot (= LOG based video).
I hope that helps and clears up in stuff you weren’t sure of!
While it may not be of too much importance to you initially, when you get serious about your video, it is useful info to know and understand so you get the best looking footage.