Changing a Background

If I was to film a movie recorded in front of a blue or green screen, is there an easy way I can replace the blue/green screen with a background of my choice like they would in films like Star Wars?

Also, if you had a camera set up on a tripod and filmed someone moving around, is there a way of removing the background IF it is the same as it was in the layer before / int eh previous frame in ImageReady?

[EDIT: removed your sig, that needs to drop around 900k at least - fig]

In software like After Effects a greenscreen removal can be done pretty easily, the basic part anyway (getting it perfect takes a bit). It can be done in photoshop as well by selecting the background color and creating a selection based on that, do some googling for greenscreen replacement and you should find some thngs there. if you're video you'll really need a tool like AE though.

on your other q...not quite sure what you're asking there.

chris

Thanks for the quick reply.

I'll see if I can acquire AfterEffects.

My second question was really just an extension of the first.
What I meant was, for example, in the animation below there's a red ball moving across a background.


The background is the same in every frame of the animation.

I was wondering is there an easy way of removing the background (in Photoshop) so that I can replace it with something else.

So basically I would want it to change it to the animation below so I can put my own bg in.


I've seen a tutorial before where they did something to the layer styles and blending option which was like using a clipping mask, but only on the parts of the layer that were the same as the layer below it.

I can't remember where I saw the tutorial or I'd go and find it..:(

If you don't understand what I mean I'll try and explain a little better.

[EDIT: removed your sig, that needs to drop around 900k at least - fig]

the only easy solution i can think of (and not really that easy) would be to create a mask for the ball and keyframe it so that it moves with the ball. I can't think of any specific ideas that would involve anything other than masking out the ball somehow.

chris