An account of a post-production technique used in the film Clarkson
I was given two film clips of actors performing in front of a green screen and instructions from the director to ..

Frame grab of Clarkson
emerging from a narrow alley.
  • create a scene where Clarkson (left) emerges from a narrow alley. He sees an angry mob. He turns to escape back up the alley but a man with a gun (right) blocks his retreat.
  • Convince an audience that the sequence was shot on location.

Frame grab of man with gun blocking Clarkson's retreat.

STEP ONE: Find a picture of a narrow alley...
This seemed OK but the alley was too wide (Clarkson could run past the gunman) and the building looked too modern so ..
With the aid of 'Adobe Photoshop' grab the right hand side of the picture and move it left. Paint out the shop sign and window panes. Add the odd barrel in the foreground to make it look like a quayside warehouse.
STEP TWO: As everything green can be made transparent we can put the Clarkson clip in front of the new background ..

in front of this.
STEP THREE: Cut a 'hole' in the background so that the clip of the man with gun (suitably reduced in size) can be seen in the narrow alley.
+ =
STEP FOUR: Because the man with the gun was filmed against a green screen, we can add a final layer - some ship's rigging.
+ =

We are looking at 4 layers..
In the foreground the Clarkson clip is on the first layer and, because the actor was filmed against a green screen, we see the other 3 layers.
Layer 2 is the new background with a green 'hole' in it to reveal the clip of the man with the gun (layer 3) and, because we filmed him against a green screen we can create a rigging background for him (layer 4).

Here is the scene from the film. You will see that it is darker than illustrated here which makes me wonder why Declan and I went to all the trouble with barrels and stuff that are unseen in detail.

But, that's filmmaking!

Mike George - January 2010.

Further reading ..