Bad Green Screen Keying

Today we learned how to key light out a bad green screen. This is when the green screen used behind a piece of footage has creases and/or shadows or anything that effects the basics of keying out the green background. When you attempt to get rid of a green screen with creases or shadows, after keying out the colour, you can still see the creases and areas with shadows, creating a bad green screen. There are however ways to fix this in both After Effects and Premier Pro.

After Effects- First of all, import and select your footage. Next select Effect < Keying < Keylight 1.2. Now use the pipette tool to select the colour you want to key out, and choose the area that would be most affected. With the bad green screen footage, you should now have a badly green screened image with creases and shadows. The way to remove the creases and shadows and be left with just the subject in the green screen is simple. First of all, change the view mode from final result to screen matte. This should change the subject to a white silhouette, with the creases and shadows being black in the background. Changing the view makes it easier to get rid of everything that isn't the white silhouette. Now alter the values of the 'Clip Black' and 'Clip White' options. This changes the values of the amount of white and black being released from the image. After messing around with these two functions, you can also mess around with screen shrink/glow and screen softness, to affect the subjects outline. Any residue left over can be simply masked out, as the remaining creases/ shadows will be at the top of the footage. To finish change the view mode back to final result and make sure the footage is up to your standard.

Premier Pro- The two methods are very similar. Again, import the footage, and select it, and add the effect 'Ultra Key' to the footage. Pipette tool the main colour of the green screen, and then change the output mode from composite, to alpha channel, to see the footage in black and white, so it is easier to get a clean green screen finished product. Go under the Matte Generation tab, and alter the transparency, highlight, shadow and pedestal tabs, to make the main subject all white, and the rest of the screen to all black. You can also alter tolerance to change the colour of the subject. Once you have altered the tabs to perfection, change the view mode back to composite to check if the desired effect has been created.

Both of the programmes make it very easy to clean up a bad green screen, and I would recommend both, although if you are working in Premier Pro, it is probably easier to just apply it within Premier Pro, but use After Effects for a more complex project.