Re: [FCP-L] Best way to Matte White Screen

Since this is getting *way* OT, I'll post this last one on the
subject, even though I don't actually see how what you say differs in
any way to what I wrote. You make my point perfectly.

You can *or course* pull a matte based on an images LUMINANCE.
Therefore defining WHITE as the "key"-color (though white is in fact
not a color) for creating transparency. Which, again, is nothing more
than what Overlay or many of the other available blend or composite
modes do, only with more control over matte density, threshold etc..
Hey, why not use BLACK next time for the same effect? Same difference.

For that matter you can even "key" an entire SKYLINE, given nothing
more than a clean BG-plate and a DIFFERENCE matte. So, why EVER bother
with that green-screen silliness? :-P

> It is quite possible to pull a usable procedural matte by keying off
> the contrast in individual color channels of the original image.

Which is merely a more technical way of saying "luma-key", yes. Only
it's not the contrast.

Bottom line: if you are using WHITE, therefore the BRIGHTNESS (aka
luminance, no?) of an images pixels to pull a matte, you are *not*
pulling a color or better *chroma* key, since white, again, *is not a
color* to begin with. You are (at best) pulling a LUMA-key. No matter
how complicated you want to make it sound. I was not trying to make
any other point. Is it a possible workaround, compromise, expedient
for a "late idea"? Sure. Would I *ever* want to *intentionally* shoot
something like that knowing that I need a matte in post? Of course
not! Never! And it has absolutely nothing to do with wanting to "get
down and dirty" or not. Just to prove what a crafty magician I am? If
you're fine with that, be my guest. I just prefer not to advocate the
idea that there is anything "okay" about shooting and wanting to key
off white, cause all you have to do is find someone in the end who's
not "lazy".

> Keying is NEVER a one-click process, even on professionally shot
> green-
> screen plates.

Sorry, but *that* is simply not true. At least if I interpret that
correctly to mean "never with just one fine-tuned keyer applied". In
which case I can only assume that you in fact have never actually had
a *professionally* shot green-screen to work with. I for one can show
you several such shots in e.g. "Life and Death of Peter Sellers" or
"Rome" that I did, both of which won Emmy's for VFX btw. Surely not
one FILTER (in the final), but one key and no additional matting, yes.
Quite often. But sure, the 20-plus-mattes-needed ones dominate
overall, yes.

But honestly? This whole thing is completely otiose in the end, since
we have absolutely no clue as to what the footage we're talking about
even looks like or how/why/with what actual type of subjects etc. etc.
etc. is was shot.

Bottom line, for Brett: if you're not getting the results you want
with any of the composite modes and/or simple luma key, then your only
other option in my opinion (again, without even knowing what it is
we're even talking about here of what the actual visual goal is... at
minimum a screen-shot would have been very helpful) would be to dive
into an app like Motion, AE, Silhouette, Nuke etc. etc., but something
tells me you'd be wasting a lot of time.

cheers,
RK

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