The keyer is probably the most dangerous color grading tool. It can achieve very cool looks, but can also completely destroy an image. When used with care, the keyer is an essential tool for the colorist. Combine it with masks and its creative value is infinite!
What is a Keyer?
A keyer is used to select (or qualify) a range of color pixels in order to modify or completely remove them. The most popular keyer is the chroma key, the technical name behind the famous green screen effect that everybody knows… whether you are in the industry or not. But what is the role of the keyer when you are siting in the darkness of a color grading room?
Keying as a Colorist
In the grading room, the keyer, or the qualifier, is often used to isolate a specific color that the colorist wants to tweak without affecting anything else in the image. When you watch software demos, presentation or tutorials, the guy will almost certainly always pick the color of a red car and change it to a crazy saturated magenta or blue or yellow, etc. Or maybe he’ll qualify the sky and change it to a the weirdest color possible. That’s a great way to demonstrate how this powerful tool works, but if you are working on real world projects, chances are you will never have the occasion to do this. Alright… Yes, in some cases, color grading can be over the top and very intense. But unless you are overdoing it as an artistic statement (weird sky color can be awesome), you want to be gentle with your pixels.
Like any tools, the keyer can be used as a technical asset, or as a creative asset.
I view keying as a technical process when I use the tool to fix problems like continuity and skin tone. Technical keying is not the most artistic part of color grading. You just have to sit down, turn your brain off and do the dirty work at some point.
Keying is a great way to fix specific inconsistencies between shots. Sometimes the overall color continuity of two shots is very close, but one element sticks out. Take these two shots:
I had to key the suit on the first shot because it was brown instead of black. I thought that was rather strange and wondered if the actor wore a different suit for some reason. Why was it different in some shots taken from the same angle? A quick google research revealed that some filters can alter the color of certain fabrics. It was confirmed later when the DP came in. He had to use filters to fix other problems on the set, but they didn’t notice the strange effect it did on the suit. It doesn’t seem like a big deal on a small screenshot, but it was very distracting when I was watching the entire spot. You don’t want a certain element’s color jumping around from shot to shot! The continuity was much better after the fix:
Keying can also be an effective tool to fix the time of the day. In an exterior scene of a short film I graded last summer, there were a few shots where you could see the sunset in the background. Like this one:
The production team ran out of time during the shoot, but they had to get as many shots as they could in camera… so they shot even if the sun was almost gone. Although this grade looked amazing, it was distracting and took you out of the story. It wasn’t matching the look I did for the entire sequence. Here’s another shot taken from the same scene:
The sky is a dead giveaway that this sequence was not shot at the same time of the day. We obviously don’t want that, so let’s fix it with our keyer. Back to the close up, I isolated the pink sky and changed it to a dark cyan blue. It was also necessary to qualify some purple skin highlights.
Here’s the matte:
The actors’ skin tones never get away without being keyed, especially if you are working in advertising. In this example (below), his face was a bit too dark, so I brought it up a bit and played with its contrast. I also added a notch of yellow and orange… but this is something that is more creative than technical. I’ll get to that in a bit.
The face is very important, but watch out for hands too. Sometimes, the overall grade will look great on the face because it has make up on it. Hands are often too red because there isn’t any make up on them or the actor simply has a high blood pressure.
Alright… enough with the technical stuff for now, let’s have fun and start being creative with keyers!
When the keyer plays an important role during the look development process, it becomes creative keying. In my case, keying mostly happens right after I’m done with my RGB and hue/sat curves, color wheels and masks. This is the moment when I stare at my monitor and the thinking begins. Like I wrote at the beginning of this article, it can also be the moment when I destroy my look. In that case I’ll probably move on to the next shot or come back later. Not every project has to rely on keying. So back to our almost finished shot…
The grade looks decent.
It looks… fine. At least, better than the original LOG image:
But how can I make this shot look good using keyers?
How could it look more artistic?
What should I be precisely keying in this image?
It’s up to you.
Here’s the thing with keyers: every shot has its own keying possibilities. We always do the same kind of vignettes, curves and color adjustments. But keying is relying on the visual content of the shot, and this content obviously changes a lot. It unfortunately means that it’s not always possible to copy it from shot to shot. If you do, be sure to review your mattes and pay attention to unwanted noise!
Check out the following video and meet me bellow for my thought process.
My goal with this shot was to combine a few subtle keys (three in this case) to get an obvious color separation while still keeping things natural and organic. I liked my grade before the keys, but as you can see in the breakdown video, it was a bit dull and flat (in terms of colors, not contrast). Autumn is a beautiful season and I wanted to emphasize that. It seemed a no brainer to key the leaves. There are yellow and orange/red leaves in this shot, but when you look at it quickly, it seems like a single orange color.
Key 01: Yellow Leaves
The first step in my color separation process was to key the yellow leaves. They were the easiest one to key. I increased their contrast, brightness and pushed the color wheel towards a rich golden yellow.
Key 02: Orange Leaves
I did the same kind of key for the orange leaves, but removed some yellow and added more red and saturation. It might be very subtle in the breakdown video, but combined with the two other keys, it is very effective.
Key 03: The Road
OK, this one was not obvious. I didn’t plan on keying anything else but the leaves… but I still found my image dull. It felt too reddish. It was lacking the opposite color, blue.
The thought of adding blue in this image might seem odd at first, but it worked out great IMO!
Whoa, that was kind of long post. Cheers if you made it to the end. I hope it wasn’t too boring and that it gave you an idea or two for your next grading session! Keep them keyers not too far.
On the same topic: Check out my Matching Shots article.
See you next time!
One last thought…