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Technique: Setting Proper Video Black Levels
Larry Jordan
[This article was first published in the July, 2006, issue
of
Larry's Final Cut Pro Newsletter. Click
here to subscribe.]
Jeff Abelson writes:
There's a FCP black-level question that's vexing me, and I'm hoping
you can give me some insight. I've read the articles on your site about
it, (click here to read them)
but I have still have some confusion.
I've cut a documentary in FCP 4.5, shot on DVCam. I'm prepping it to take
to an online facility to output to DigiBeta for delivery to PBS, who licensed
the show. Aside from the PBS specs in general making my brain melt -- the
one item I'm particularly unclear about is black levels. The online
facility took a look at my show (which looks great on my NTSC monitor),
and told me that too many of my clips have black levels that are not at
zero, and so before they do their output, I have to bring the blacks down
in each clip to zero, which I've now done. But the visual result on
the NTSC monitor (and on dubs played on my TV), is that the image is WAY
too dark/contrasty.
I also understand that the blacks on the DigiBeta need to be at 7.5, and
that this will happen in the output process.
My question is this: is the image in the zero-black sequence the
actual level of visual darkness we will see broadcast on PBS -- or will
the zero to 7.5 conversion when going to DigiBeta brighten the image so
it will look like it used to?
In other words, is the 7.5 just another way of describing the same level
of digital blackness in my zero-black sequence (meaning it will still look
the same to the eye), or will they actually be brightening up the image
on the DigiBeta?
If the latter, then I'll relax. If the former, I'm worried. And
believe it or not, the online facility has not been able to adequately answer
this question for me (I know, I should find another facility, but I'm just
about out of time/money for this).
Larry replies: Jeff, ALL black levels for digital video are set
to 0 in Final Cut -- this is the normal level for digital
video black. So, your post house is correct.
Analog black for NTSC - US is 7.5 IRE. This is analog only.
Your black levels will automatically change when dubbing from a digital device
to an analog device. This is done either thru your capture card or at the
output of your deck, whichever you use, so you don't need to worry about it.
The DigiBeta is a digital device. So send your sequences to it with blacks
set to 0. When it creates an analog output, the Digi deck
will automatically add the necessary setup to raise the black levels to 7.5
IRE.
If your images look too dark, I would suspect the monitor is not calibrated
properly.
This tip is from the July, 2006, issue of "Larry's Final
Cut Pro Newsletter," a very cool FREE monthly Final Cut Pro newsletter
-- subscribe at Larry's web site: www.larryjordan.biz.
Larry Jordan is a post-production consultant and an Apple-Certified
Trainer in Digital Media with over 25 years experience as producer, director
and editor with network, local and corporate credits. Based in Los Angeles,
he's a member of both the Directors Guild of America and the Producers
Guild of America.
Any references to trademarks or products are used for editorial
purposes only. Text copyright 2006 by Larry Jordan and Associates, Inc..
All rights reserved.
Larry Jordan is a post-production consultant and an Apple-Certified Trainer in Digital Media with over 25 years experience as producer, director and editor with network, local and corporate credits. Based in Los Angeles, he's a member of both the Directors Guild of America and the Producers Guild of America.
The information in this article is believed to be accurate at the time of publication. However, the author assumes no liability in case things go wrong. Please use your best judgment in applying these suggestions.
The opinions expressed in this article are solely those of the author. This newsletter has not been reviewed or sanctioned by Apple or any other third party. All trademarks are the property of their respective owners and are mentioned here for editorial purposes only.
Links to my website home page or this article are welcome and don't require prior permission.
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