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Can someone please explain DI?


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#1 Daniel Moore

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Posted 10 November 2008 - 04:42 PM

What is DI? I think I am correct in saying it means "Digital" something....but if someone could really elaborate on it, like explain what it is, when it's needed(or if it's preference rather than necessity), and give me some movie names that have DI so that I can have some reference, I would appreciate it. I have actually been told that the movie A Very Long Engagement had a ton of DI, so I should watch that again, but any other examples would be great. Thanks.

Edited by Daniel Moore, 10 November 2008 - 04:44 PM.

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#2 Jamie Metzger

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Posted 10 November 2008 - 04:58 PM

Digital Intermediate: http://en.wikipedia....al_Intermediate

The "film" guys consider anything involving telecine/grading/laser printing a "DI", because literally, you are changing the medium from Film (optical/analog) to Digital. Telecine will digitize film so you can edit non-linearly. From there you can do film outs, laser prints, and deliver on HDcam/digibeta/beta/dv...etc

Read up!
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#3 Phil Rhodes

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Posted 10 November 2008 - 05:03 PM

Started to write a reply, then realised this was far better:

http://en.wikipedia....al_intermediate
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#4 K Borowski

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Posted 10 November 2008 - 05:20 PM

DI's for film output are, in the opinion of this individual, an underhanded attempt by digital chip manufacturers to undermine the market and convert everyone to digital by making film-originated media, look bad.
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#5 Matthew Buick

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Posted 10 November 2008 - 05:30 PM

DI's for film output are, in the opinion of this individual, an underhanded attempt by digital chip manufacturers to undermine the market and convert everyone to digital by making film-originated media, look bad.


Sheer melodrama.
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#6 K Borowski

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Posted 10 November 2008 - 07:24 PM

Sheer melodrama.


I'm sorry. Am I treading upon your usual turf?


BTW, shot that first foot of 16mm yet?
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#7 Glen Alexander

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Posted 10 November 2008 - 08:04 PM

I'm sorry. Am I treading upon your usual turf?


BTW, shot that first foot of 16mm yet?


Karl,

Should I repost your rant about not going off topic?
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#8 Bruce Greene

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Posted 11 November 2008 - 02:58 AM

DI's for film output are, in the opinion of this individual, an underhanded attempt by digital chip manufacturers to undermine the market and convert everyone to digital by making film-originated media, look bad.


Karl, I'm starting a DI next week. I hope the director doesn't read your post! You may have a point though, the telecine dailies look awful, except for the last two weeks of filming, when I never got the dailies:)

I'm sure the DI will look fantastic though.
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#9 Matthew Buick

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Posted 11 November 2008 - 09:31 AM

I'm sorry. Am I treading upon your usual turf?


BTW, shot that first foot of 16mm yet?


Actually yeah, 200ft of EXR 50D, and a further 100ft of 7219. Not to mention an unsuccesful roll of 5247.




Karl,

Should I repost your rant about not going off topic?


Good one! :lol:

Edited by Matthew Buick, 11 November 2008 - 09:34 AM.

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#10 Paul Bruening

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Posted 11 November 2008 - 10:48 AM

It does seem peculiar to digitize an image that originated on film. One might assume that it would make more sense to just originate in digital and skip all the hassles of film. But, from what I've learned by doing my own scans is that many of the lovely qualities of film hold up and transmit through into the digital images if you work above what I call, "the resolution threshold". A 2K scan, while enough to make a "usable image", doesn't quite capture enough detail of the actual dye and grain sites to carry that "screen crawl"-textural element. As well, 2K scans don't capture enough grain/dye detail to transmit the subtle variations of luminance and chrominance that make the brights and darks differentiate in that subtle but detectable way that, often, only cinematographers or color timers can see. Worse than this is HD telecine. Not only is the resolution low, the images are often further compressed.

My conclusion has been: If you really care about the 35mm, DI image, scan in 4K or higher. If you just need a cheaper picture that's "good enough" then scan 2K, telecine or low-res datacine. That's only opinion. Artistic judgment and nothing more.
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#11 Serge Teulon

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Posted 11 November 2008 - 11:00 AM

Going past the usual negative opinions about DI, as I'm about to do my first ever DI I'm finding this post quite interesting,
Is there any operative pot holes that anyone can help me not fall into? Please don't include the obvious "Your going from film to digital, so that is already one hole" ;)

Cheers
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#12 Paul Bruening

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Posted 11 November 2008 - 11:04 AM

What are your ideas about the transfer paths and resolutions that you intend?
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#13 K Borowski

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Posted 11 November 2008 - 01:17 PM

OK, we all agree that DI is easier.

With the exception of movies like "Oh Brother, Where Art Thou", "Amelie", or "Smallville", where DIs were used in original innovative ways, or DIs that are used to save on generations you'd need for an optical blowup (personally I still like optical blowups better, like "Gladiator", but I see why DIs are useful here), what movies look better because they went through a DI than if they were just optically printed? Has there been one, just one, film that any of you have seen that was a 2K DI that honestly looked as good as it would've were it finished optically?

I honestly can not understand why movies like "United 93", or "The X-Files", or "The Proposition" where maybe 5-10% of content was digital, went through DIs.

To boot, they're still more expensive than an optical finish.


I am all for more creative control, but not when it comes at the price of final image quality. Having had the chance, too to see some gems of movies like "American Gangster", and "There Will Be Blood" this past year has only strengthened my convictions that DIs still aren't getting it right.

This is why, while I agree with Paul that 4K or even 3.2K DIs will solve the problem, I am against the DI process because you just cannot get the DI guys to give you a reasonable price on a 4K DI unless you're making the next "Dark Knight" movie :blink:

Further, I'd say that there is maybe one scanner out there that would make it feasible, not easy, to do scanning of an entire movie onesself. This is the Kodak HR500, and it'd have to be modified to scan 4-perf. at a time rather than 8-perf.

I've spent too many all-night sessions scanning 35mm stills to know that 99% of scanners suck, and that it really is intentionally that way because the people that make the scanners make the digital cameras.

Even Nikon 5000 scanners, while fast, are so temperamental and change settings on their own so sporadically that it really has to be intentional.

The only way around this problem is to get a $20,000+ scanner, which labs and telecine houses can afford, but you and I cannot. Obviously, none of the cine scanners are going to be available on the second-hand market, except old ones, so the only hope is to snag a high-end still scanner, now that the bottom has totally fallen out on film equipment in still photography on the used market.
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#14 K Borowski

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Posted 11 November 2008 - 01:23 PM

Going past the usual negative opinions about DI, as I'm about to do my first ever DI I'm finding this post quite interesting,
Is there any operative pot holes that anyone can help me not fall into? Please don't include the obvious "Your going from film to digital, so that is already one hole" ;)

Cheers


Serge, I am not trying to say that a DI itself is a hole, just that the actual scanning is implemented so badly most of the time, that you really need to shop around to try to find the best people doing it.

A big problem with scanning is sharpening. You have to find a pleasant compromise between over- and under-sharpened scans. Undersharpen your scan and the image will be mush, oversharpen and you'll literally start to see the lines from the scan head as it runs back and forth across the surface of the film.

I've found, from my work with scanning, exactly one lab that did a good job with its scans, another that was OK.

So this step is the most-critical. Try to find a lab that will actually let you watch them do a test scanning process and will let you adjust the controls for your film.
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#15 Bruce Greene

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Posted 12 November 2008 - 01:07 AM

Serge, I am not trying to say that a DI itself is a hole, just that the actual scanning is implemented so badly most of the time, that you really need to shop around to try to find the best people doing it.

A big problem with scanning is sharpening. You have to find a pleasant compromise between over- and under-sharpened scans. Undersharpen your scan and the image will be mush, oversharpen and you'll literally start to see the lines from the scan head as it runs back and forth across the surface of the film.

I've found, from my work with scanning, exactly one lab that did a good job with its scans, another that was OK.

So this step is the most-critical. Try to find a lab that will actually let you watch them do a test scanning process and will let you adjust the controls for your film.


I'm confused Karl: Are you talking about a still photo lab making film scans, or a motion picture post house making a scan for DI?

I don't think a DI scan would add any detailing/sharpening until the color grading session.

By the way, I've been very happy with my scans from my Nikon scanner...using the vuescan software. I can't imagine doing optical prints again for stills. Why should movies be different?
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#16 Serge Teulon

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Posted 12 November 2008 - 05:33 AM

Karl, I hear what you are saying and I appreciate that you are a traditionalist at hand. I'm am too.
Until now I've always taken the traditional route in lab to post. But I'm looking forward to experiencing at first hand with a system that, outside of the literature available, I know nothing about.

The scanning is a potential pot hole that I didn't know about......is Bruce right in saying, in motion pictures, that sharpening does not take place at scanning?
This is becoming more and more interesting.
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#17 Adrian Sierkowski

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Posted 12 November 2008 - 07:50 AM

As far as I know; and you should take this as anecdotal evidence, the sharpening happening in a DI is done via the software. I believe it may be controlled as part of the "grain reduction," or at least that's what I recall hearing from my colorist awhile ago when we spoke of that (keep in mind I've been awake for 23 hours now working my one pain in the ass "normal job" shift. .. 8 am till 8 am. . . and also that we were speaking of scaning S16mm @2K via a Spirit DataCine to DPX). Whether this is true for all facilities or not, I cannot say. I would recommend just phoning up the house you're planing on DI-ing with and asking them.
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#18 K Borowski

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Posted 12 November 2008 - 03:31 PM

I'm confused Karl: Are you talking about a still photo lab making film scans, or a motion picture post house making a scan for DI?

I don't think a DI scan would add any detailing/sharpening until the color grading session.


I'm talking about all film scanning. You'd be surprised how even the most expensive scanners can be configured poorly.

Unless you want to see the scan lines, unfortunately, there is always going to be some degree of sharpening correction.
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#19 K Borowski

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Posted 12 November 2008 - 03:35 PM

Without sharpening or scanner file correction software, you can still get this. . .

http://www.christies...bjectID=5054063

I can't blame digital for this, but the same principals are still involved in scanning today. . .

Totally off-topic, but does anyone want to hazard a guess as to how they made this photograph in space in 1966?

Edited by Karl Borowski, 12 November 2008 - 03:39 PM.

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#20 K Borowski

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Posted 12 November 2008 - 03:47 PM

As far as I know; and you should take this as anecdotal evidence, the sharpening happening in a DI is done via the software. I believe it may be controlled as part of the "grain reduction," or at least that's what I recall hearing from my colorist awhile ago when we spoke of that


Sorry to hear you've been up so long. By my math 8 AM to 8AM is twenty FOUR hours, so it's definitely affected your perception of time ;-)

Problem is, is that there's a lot of processing done before you even see the file with scanners. Otherwise your scans would look like the moon picture.

So, to some extent, digital interpolation is good and necessary, but what is bad is when it is adjusted to induce a phenomenon known as "grain aliasing". Also problematic is lower-than-necessary file resolution.

I'd just recommend testing a lot of different scanners and asking them to tweak things you don't like, using a contact print's look as a reference point.

Labs would probalby be happy to do a short test of their work for you to compare.
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