[Tig] DVNR settings theory and practice -- advice needed

JSnopes at aol.com JSnopes
Sat Oct 6 22:32:48 BST 2001


I need a bit of advice re DVNR settings.

I'm working on remastering a documentary from the Seventies, with very 
pretty 7242 color, and quite a bit of nice grain (much of it was pushed 
heavily).

The original transfer was a flat transfer on a Spirit from the 16mm 
interneg (A&Bs weren't practical to work from) to D5HD24P.  This was 
downconverted (via Teranex) to Digibeta.  (The D5HD master is being 
stored, not needed now.)

Thousands of dust fixes were done in an Avid (uncompressed).

Then tape-to-tape color correction and noise reduction were done (daVinci 
2K, DVNR 1000).

Color correction is beautiful.  And the noise reduction looks (mostly) ok 
when viewed on a 19" Sony BVM20F1, as it was in the telecine suite.

However, when the same tape is viewed on a calibrated 29" Sony monitor 
(component in, from SDI via AJA D to A) three things are apparent.

First, and most noticable: there's a sort of grainy veiling over the 
image, mostly on scenes where higher DVNR settings (14 Y, 14 C) were 
used.  (These were used often.  No Y or C prefiltering was used, as the 
colorist felt that they are to be avoided.)  It looks like a 
slowly-moving film of grain superimposed over the image.

Second, (mostly) on scenes with extreme contrast ratios, with, say, a 
side-lit face, when the face moves, the bright side of the face and the 
dark side of the face will move separately, as if they are shifting 
tectonic plates -- the dark side's movement lagging a couple frames 
behind the bright side.  This can be quite annoying.  Again, less visible 
on the 19" monitor, but there if you are attuned to it.

Third, no aperture correction was used.  This may have been a 
misunderstanding, as this colorist rarely does tape-to-tape, but 
regularly uses aperture correction on their Spirit-to-tape work.  This 
results in a slightly mushy looking image -- when I run it through our 
DVNR for aperture correction only (a 2 or 3 on H and V settings) it looks 
(to me) much better.

So, what I'm really wondering is:

What are the usual limits (i.e. highest settings you'd use) on a DVNR.  
To me, from some rough tests, it seemed like a 9 Y and a 9 C was about 
the limit (on this grainy material).  Is prefiltering something to be 
used or avoided?

What sort of aperture correction (standard, not advanced) do most of you 
like (both H and V) for material that you've noise-reduced?

Any other advice as to the use and overuse of DVNR?  It's a great box, 
but can be dangerous if overused.  (BTW, purpose of this master is DVD 
release.)

Anyone used the new DVNR card yet (it's being beta tested now, I hear)?

All advice greatly appreciated.

Jeff "noisy, and grainy too" Kreines






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