Howdo all, yep that time has come for another blog entry, something that's a bit of fun.. Green Screening.

For those of you that are wondering what Green Screening (also known as Chroma keying) is, it's a simple technique for making you appear somewhere your not on video.

Anyone who has seen a weather forecast or a new's show on TV will have seen green screening in action... Or not as you can't see the green screen once the editing has been done..

Anyway, here's what a green screen looks like.. Or part of it as it is rather big being 3m x 1.6m.

Ideally your screen should hang nice and flat with no creases showing... My screen was quickly hung in a way too small room just so I could have a quick play.. I've not told my wife yet that I want to turn the spare bedroom into a recording studio yet

So having filmed your bit of footage, you now need to do some editing.. I use Sony Vegas Pro 11 for all my video edit (more about Vegas in a later blog entry), as you can do so much in it.

If we zoom in a bit you can see me and the bit of backing footage I'm going to use in the time lines.

You need to make sure your backing footage is below the green screen footage or this won't work.

Now to add the "effect" which will make the green screen vanish.

In Sony Vegas I click on the "Video FX" tab which brings up a whole host of video effects options.. Chroma Keyer is the one we want.

As you can see you do get a choice of different types of Chroma Keying, you can do it using a red or blue screen, but green works the best which is where "green screening" got it's name I guess.

The last 3 GS options are my own custom pre-sets.

For this demo I dragged and dropped the "GS option" onto my GS bit of footage in the timeline.

Which gives you this. The GS has vanished and been replaced by your bit of backing footage.. It's not looking that good however, the backing is a bit dark and you can see the folds in my GS (which is why you need them as smooth as possible).

When you drag the GS option from the Video FX tab onto your GS footage this window also appears so you can tweak the GS effect.

You need to tweak the Low threshold and High threshold a bit, I also add a very small amount of blur..

Until you end up with something like this.

A close up..

So there you go, my short guide to Green Screening..

If your wondering why this blog entry is called "A stupid guide to Green Screening", this short video will give you an idea of what's possible..

The only limit is your imagination