EnigmA Amiga Run 1997 July/EnigmA AMIGA RUN 20 (1997)(G.R. Edizioni)(IT)[!][issue 1997-07 & 08][EAR-CD IV].iso/lightwave/lwmlist/96.lightwave-0408/[e-mail] _Fri Apr 12 09:39:52 1996.msg

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Date: Fri, 12 Apr 1996 06:39:50 -0700
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From: Andrew Hofman <[e-mail]>
To: Multiple recipients of list <[e-mail]>
Subject: Re: superblack from LW
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>Andrew!
>
>[For the PAR] Can that SETUP=0 be set to -5 (super black = less than 0 IRE)
>and can the same be true for the PVR?
>
>I just wrote an inquiry here regarding anims over such black
>values and didn't see this thread yet.
>
>Is there any other way?  For example, I'm having anim frames
>from a PC transfered to bernulli (amiga format) and then
>converted into a Flyer clip... anyway to sub-black them?
>
>

Sounds logical, but I don't think -5 will work. We're talking binary here so
it's either 0 or 1, on or off. There might be a trimmer pot somewhere on the
board that sets zeroblack reference and could be cranked down for
superblack, but I don't know. Call DPS to find out.

The PVR hides all this Setup=0 nonsense from the user by providing a button
to do the same thing. There is a line in its config file that states SETUP=0
or 1, but there is no reason to fool with it.

As far as the Flyer, I can't tell you as I have never actually used one. But
my experience with the Toaster would indicate no, it can't output animations
over zeroblack. It is true that the Toaster will grab, save and display
Framestores (not RGB files) with zero or superblack in them, but only for
images grabbed from an outside source. LightWave and TPaint cannot generate
such images. One time I thought I came up with a cheat for this, and tried
using a framestore with superblack as a background image in LW. But it
simply elevated the frame to 7.5 IRE. This makes sense, considering the
lowest RGB value LightWave can deal with is 0,0,0. And the Toaster is
internally calibrated so that 0,0,0 is locked at 7.5 IRE. There is no
provision in LW for negative RGB values. Framestores somehow handle this
differently, but even their superblack is numerically inaccessible to LightWave.

Before I had the PAR/PVR, I used the following approach. It requires an
outboard switcher or second Toaster.

1) Obtain a source for a zero or superblack signal, like a TBC or camera
with its setup cranked below normal.
2) Render your animation so it is deliberately overexposed, making it easier
to key over 7.5 IRE.
3) Key the animation straight off your Flyer and over the superblack signal.
Use a dissolve transition to control the animation's brightness. This way
you can bring it back down to broadcast limits (using a W/V scope), yet
still obtain a decent key despite rendering over 7.5 IRE black. Now don't
touch the T-bar!
4) Lay the animation off to tape.

I'm not sure, but a second switcher may not be needed if you're using a
Flyer. I would, however, check for trailing-edge artifact problems when
using the Toaster for keying.

If the end client is using a nonlinear system or has three source decks, you
could render out an alpha channel anim and sidestep keying altogether.


Andy Hofman
LumaQuest Productions
Animation and Dual Raptor 3 Rendering
[e-mail]
513-643-7333