Technical Journal (Green Screen)


Have you ever been watched an unknown creature or an impossible scene in a film? That's the reason why we use green screen to achieve certain effect that can't be shot on location or at the same time.

There are a lot of things what we need to take care of while we are shooting with green screen. For example : lighting, shadows, colors between foreground and background, etc. Now, what I would like to talk about more is how can we solve and key out a disturbing certain area from our green screen background.

Here is our original footage with green screen background. What the problem in it is the dark crease behind on the green screen. Of course, we need a clear matte to key out all the green. So, what we need to do first is to remove this crease behind and make a clear green screen background. It's one of the problems what we can easily get when we shoot with green screen clothes backdrop.

Basically, we need to prepare a shoot of only green screen background ( without actors) with same camera setting and same lighting at the same time. So, we got this shot below.

Now we can manage to correct green screen in Adobe After Effects. All the things what we have to do in AE is just playing around with layer's moods and pull matte.

So, here is a green screen video done by me.

                                      

The problem is her curvy, messy hair. It's a bit tricky to get a clear matte of her hair. how do I solve it? I pulled out two mattes, one is a clear matte for her hair with noisy body and another one is nice matte for body but not for hair. Then, I merged these two layers together and used where the matte is clear enough.