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Sharpening and Grain in DI


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#1 John Jaquish

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Posted 12 May 2016 - 09:18 PM

I'm currently grading a project shot on BW 35mm. "DI" may be a misnomer here as it's in HD Prores, but anyway... I had a question about the general use of sharpening and its effect on grain.

 

From my understanding, adding sharpening in post on projects captured digitally is somewhat common (?), but I'm wondering if that's the same for projects shot on film. That is, should sharpening be more of a corrective measure for shots that need it, or is it a routine step in the grading process (and is that different between digital and film projects)?

 

Additionally, how is that tied to degraining? Do most films shot on film go through a degraining process? In that case, I realize sharpening would be applied after the degrain. I've been playing around with the unsharp mask in After Effects and finding that it's accentuating the grain, which is probably no surprise. Though, I'd prefer not to go through any sort of degraining for this project.

 

In a nutshell: Is digital sharpening a routine step for projects shot on film, or is that only if degraining has been applied (corollary: how common is degraining)?


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#2 David Mullen ASC

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Posted 12 May 2016 - 09:52 PM

There is probably a standard amount of mild sharpening for film recorders putting 2K files onto 35mm, but in the D.I. suite, sharpening is done on an "as needed" basis, some people use it more liberally than others. Same goes for grain reduction. So many movies shot on film are neither sharpened nor degrained in the D.I. except for occasional shots.

The exception would be IMAX's DMR blow-up process which does a grain / noise process followed by sharpening, the theory being that grain is more distracting on a large IMAX screen.

When I did the D.I. for "Jennifer's Body", shot on film, we would often isolate the eyeballs and do a slight sharpening, which helped make the close-ups look sharper without getting more grain in the skin areas (and it was hard to see grain in an eyeball-sized area.)
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#3 Shawn Sagady

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Posted 12 May 2016 - 10:00 PM

That's super helpful information Dave and a good tip.

Edited by Shawn Sagady, 12 May 2016 - 10:01 PM.

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#4 John Jaquish

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Posted 12 May 2016 - 10:03 PM

Great. Thanks, David!


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#5 Matthew W. Phillips

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Posted 12 May 2016 - 11:44 PM


When I did the D.I. for "Jennifer's Body", shot on film, we would often isolate the eyeballs and do a slight sharpening, which helped make the close-ups look sharper without getting more grain in the skin areas (and it was hard to see grain in an eyeball-sized area.)

I thought you shot that film digitally? On the Phantom or the Red One?


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#6 David Mullen ASC

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Posted 12 May 2016 - 11:54 PM

We shot that in 3-perf 35mm -- one scene had some 1000 fps Phantom shots, that's all that was digital.
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#7 Tyler Purcell

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Posted 13 May 2016 - 10:15 AM

Sharpening masks generally don't hold up well, they can get noisy very fast. The side effect is the area that's sharpened will have a cross-grid of noise that is unexpected. Mild sharpening like David describes, is used but nowhere near as frequently as de-grain or "softening" of the image. All of the artists I've worked with, de-grain film without hesitation. It's kind of the go-to problem fixer for film grain, which is quite sad. Adding noise to film through the sharpening mask, is rare. I can see if your transfer wasn't good, there maybe room for sharpening, but with a good transfer, film should offer plenty of crispness, that you should be more interested in backing off, rather then adding.
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#8 John Jaquish

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Posted 13 May 2016 - 10:36 AM

Thanks Tyler. Yeah, I certainly am not finding any lack of sharpness in our footage; I'm not sure why I was thinking that adding sharpening may be a routine operation in grading (was probably reading a lot of stuff on grading digital projects and wanted to make sure I wasn't skipping something). There's maybe four shots in the film where we used a particular wide lens that appears less sharp than the other shots, that I may play around with sharpening on.

 

On the other hand, we also have a few shots that are particularly grainy. I was playing around with the "remove grain" filter in After Effects, and just didn't like the softer result (admittedly, this was my first time using the filter, so I'm no expert, but I spent a few hours experimenting with it). Ultimately, I'll choose the grain over the soft image. Maybe if this were in color, I'd be more inclined to take out some of the grain, but not with black and white.


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#9 Bruce Greene

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Posted 13 May 2016 - 02:04 PM

from my experience...

 

For stils shot on film I always sharpen.  There is something lost in the scanning process that makes scans look a bit "dead" compared to how I expect it.

 

I haven't shot on film for a while ... but, when I last did, the colorist was not enthusiastic about sharpening the scan.  In the end we didn't, and I always thought that we'd made a mistake here.  It was a 2k scan, and maybe a 4k scan would have been different.

 

As for digital origination, I almost always sharpen my digital still images, but, I'm still shooting 13mp 5D :)

For films shot on Alexa 2k, I've experimented with sharpening, but in the end did not.  It looked great on the small display, but not so good in a theater.  Perhaps a tiny bit would have worked fine, but ultimately would have delayed delivery of the film.  Some individual shots were sharpened and looked fine in the theater.  For a different project (this was a romantic comedy) I might have sharpened the entire film a tiny bit to give it a little bit more punch.

 

In the end, the best thing you can do is create a short test of sharpening and project the DCP in a proper theater to see the effect.  Especially since you've shot B&W film.  B&W optical prints have a pretty big punch in the highlights that might get lost in a scan.  Sure, you'll see more grain, but you might really like the effect.


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#10 John Jaquish

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Posted 13 May 2016 - 03:35 PM

Thanks for your ideas, Bruce. I noticed you had posted something similar in the General Discussion section, but I figured it might get more discussion here.

 

Yeah, I'm being pretty conservative for now with any sharpening, only using it on a few shots. I'd love to be able to test some of this with a DCP.


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