Green Screen

A green screen is a surface of green behind the main action at the front. It is used for when you want to add a different background behind that could not be produced by filming the piece 'normally'. It is done by placing a green screen or wall behind the main piece of action, allowing the editor to place another piece of footage in place of the green area. It is important for the people in the action at the front, not to be wearing green; this is because, one colour is chosen to be removed, in this case, green. If the person also wears green, their clothing will also show the background image.  This technique is commonly used for weather forecasts, instead of the presenters standing in front of a large, moving map, they are instead, most often, pointing at a blank green screen and the images are edited in at a later date. This can also be done with a 'blue screen'. These are the two colours chosen because it is thought that they are the furthest from skin colour.