OUDF504: Key-light Tutorial

On one of the tutorial, we learnt how to key an actor out of a green screen. This is fairly simple to do and it didn't take too long to get my head round it.

figure 1

To get a clean key out of the image above, the first thing I did was use the Screen Colour ink dropper in the Key-light effect, I then selected the green screen colour so the green screen would disappear and turn black. There are other options I still need to do to separate the actor from the back ground. 

I used the screen pre-blur option and changed the value to 3 to smooth things out on the edges. Raising the clip black and lowering the clip white on the screen matter option to 58 and 75 equalised the levels and the image looked like (figure 2) at this stage.

figure 2

I further cleaned up by using screen shrink/grow attribute and changed it to -0.8 and it worked perfectly. I then Adjusted the replace method to hard colour for lighter blending with the green spill. For final refinements, I learnt how to use the simple choker, I increased the value to about 0.75. The last step was keying out the actor, this is called a garbage matte. 

This removed all the back ground leaving only the area that I selected over. My footage was now ready to be composited to any background I wanted.