Run shader on screen after other shaders have run?

[QuantumDoja]

Hi, I have two different objects, a man and a car, each has it's own shader and both display fine on the screen.

Now, Is it possible to apply a shader to the whole screen after the man and car have been rendered?

Would I have to render the output somewhere else first, run another shader on this and then draw this back to the screen?

Any pointers would be a great help!

Thanks