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Do DV cameras record "superblacks"?

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glenn chan
Do DV cameras record "superblacks"?
on Sep 18, 2005 at 5:37:22 am

I think all DV cameras record digital black level at 16. However, they record this with compression. I suspect the compression pushes some bits slightly below 16. In Vegas, I see this happening on Vegas' histogram. But this assumes that Vegas' histogram is correct.

So my question is, do DV cameras record superblacks?

2- The question above is a bit assinine, but I can think of a situation where it might matter. FCP may have a weird bug in the way it handles superblacks. To see it:
Put the NTSC bars and tone generator in a NTSC DV sequence.
Add the 3-way color corrector.
Drag the black level slider slowly- the darkest PLUGE bar will disappear and reappear! The vectorscope clips superblacks no matter what, even if the footage actually has superblacks.
Perhaps something similar can happen with sueprblack values. Haven't tried this myself yet.


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Matte
Re: Do DV cameras record "superblacks"?
on Sep 18, 2005 at 12:10:20 pm

Well, to directly answer the question in the subject line:

Digital video (DV included) is designed to be recorded with "Zero black" (super-black) as opposed to analog, where the blacks are intended to be at 7.5 units above "zero".

Many (pro and semi-pro) DV camcorders have a menu setting to allow them to record their black-levels at 7.5, but that can cause problems if, at a later time, the "edit" is AGAIN readjusted to add "7.5 black" if being dubbed to analog.




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glenn chan
Re: Do DV cameras record "superblacks"?
on Sep 22, 2005 at 3:54:55 am

Hi Matte,
In case I wasn't clear: I was talking about digital units, not analog.
I'm not sure exactly what the proper name for digital units is, but DV records Y' Cb Cr and the values range from 0-255. Digital black level should be at 16 for Y'. My question is whether cameras record values under 16 (because of the compression).


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