[SLUG] Blue screen

[john at johnallsopp.co.uk]

Completely off topic, but technical nonetheless .. I noticed on the
ITV weather .. well, two things:

1) the blue screen behind the weather presenter had vertical fault
lines, as if it were folded and put away at night, and more
interestingly

2) the presenter cast shadows onto the weather map. How's that work
then? I thought the blue part was replaced entirely by a new image.
Could it be they are actually projecting onto a physical screen
(perhaps from behind), or is there some digital tomfoolery going on?

J