The difference between 4:2:2 and 4:2:0 along with 8-bit vs 10-bit was a hot discussion back when the Panasonic GH5 was announced. It was the first small form factor camera to offer 10-bit 4:2:2 internal, and it confused a lot of people. It still seems to confuse a lot of people, but even if you do understand it, can you even really see a difference between 4:2:2 and 4:2:0?
While only offering 8-bit colour, not 10-bit, Gerald Undone decided to compare 4:2:0 recorded internally on his Sony A7III with external 4:2:2 recorded using the Atomos Ninja V to see if you can really see a difference in the footage. It may not be as significant as you might think.
For a quick refresher, with a more complete explanation of what the numbers all mean, have a read of this. But essentially it’s how cameras determine the colour that goes into the final footage. The maximum possible is 4:4:4, and it contains all of the luma and colour data that your camera saw. 4:2:2 and 4:2:0 discard some of the colour data and then interpolate the missing data. It is an exercise in saving bandwidth, allowing for smaller file sizes.
While once the leaders in full frame small form factor video, Sony seems to be slipping behind these days, only offering 8-bit 4:2:0 internally or 8-bit 4:2:2 externally through HDMI to a recorder. Canon’s EOS R offers 10-bit 4:2:2 external recording (although it does crop quite heavily), and the Nikon Z6 and Z7 will soon offer 12-bit raw video recording externally.
When it comes to 8-bit video, one would think that the difference between 4:2:2 and 4:2:0 might be quite significant. More data is always better, right? But as Gerald’s tests show, the difference isn’t anywhere near what some of us might think. In fact, he had to apply two pretty extreme grades to the footage in order to see any significant difference at all when playing back the footage.
In most daily use cases, you likely won’t see much difference between 4:2:2 and 4:2:0. For more everyday scenes and outdoor shots with fairly low colour contrast and smooth gradients from one colour to another, they’re largely going to look identical, and it really won’t make a difference which you shoot.
But does that mean that 4:2:2 is just a useless gimmick? No, of course not. There are times when the difference can be quite noticeable. For shooting, editing and viewing footage yourself, sharp contrasty edges with big colour differences can be quite obvious.
You can see some examples of this here showing text on a computer screen where the issues are apparent. While 4:2:2 doesn’t completely eliminate the problem in that case, it is improved over 4:2:0. Ideally, 4:4:4 would be best, but we’re not quite there yet with these types of cameras and recorders at this budget.
Green & blue screen chroma keying can also benefit from the extra colour data of 4:2:2. If you’ve ever tried to green screen something using 4:2:0 footage, you’ll know exactly what I mean. You get all kinds of odd artifacts in the background around the edges of your subject and it can often result in a halo that’s tricky to clean up. Again, 4:4:4 is the ideal, but the extra colour information of 4:2:2 footage definitely makes for a cleaner key over 4:2:0.
Ultimately, is the difference worth it? That’s going to depend on your needs. What is the footage that you’re going to be shooting and how are you going to be using it? Just shoot, edit and deliver, possibly not. But if you’re doing any kind of compositing or effects, you’ll definitely see some difference.
Can you see a difference in the footage Gerald shot?