Pulling A Clean Key When The Talent Wears Green
Green on Green Screen
So I was shooting the video announcements this week when about half way through I realize this person has green on their shirt. It’s a floral patten and it has a lot of green in it. I’m on a time crunch and this person is senior leadership at the church (Executive Pastor’s Wife) so I decide on the spot I can “fix it in post”.
So today I’m in post and I have to figure out what to do. Here’s the shot I have to work with.
Primaate Attempt 1
The first thing I did was try my favorite keyer, Primatte. My first thought was to use the Alpha tools in Primatte to plug the holes in the matte, but I wasn’t happy with the results I was getting. By using the alpha tools and cleaning up the foreground I couldn’t get it to where I wanted to. Some of the plugged holes had some goofy edges and the spill was unacceptable. Here’s what it was looking after Primatte.
I tried Keylight too and couldn’t get the holes in the matt plugged and maintain the edges. I knew this wouldn’t be a one filter/ one layer fix. I needed to create a good inner matte to build off of. So here’s what I did.
1. Create a garbage matte around the talent. They sat pretty still during the shoot so it wasn’t a problem.
2. Duplicate the layer.
3. On the top layer I applied Color Key. I sampled the background close to the talent and then raised the tolerance to get the background without getting my foreground talent.
4. I applied Simple Choker and set the value to a small positive value. This shrunk the matte to just inside my talent. Since it’s based on the key it moves with them. No rotoscoping needed.
5. On my top layer I then changed the blend mode to Alpha Add. This blend layer only affects semitransparent pixels. It adds the alpha values. This is needed because if you have two layers that have 50% transparency on top of each other they don’t add up to 100% transparency. This fixes that. [EDIT] In recreating this project I don’t know if this step is needed. If you leave the blend mode to normal it basically creates in inner matte
6. On my lower layer I applied Primatte focusing on getting a good key on the edge since my top layer was taking care of the core matte.
Here’s the final after the core matte was created and the key pulled. Looks is used to grade the shot:
