Setting Proper Video Black Levels

Posted on by Larry

[ 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.

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