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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Resolution equivalent for 35mm (Page 1)

 
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Author Topic: Resolution equivalent for 35mm
Dan Chilton
Expert Film Handler

Posts: 191
From: Springfield, MO
Registered: Mar 2004


 - posted 05-01-2006 04:30 PM      Profile for Dan Chilton   Author's Homepage   Email Dan Chilton   Send New Private Message       Edit/Delete Post 
One of the biggest comment I get at our theater when people see that we're using 35mm film reels is: "Wow! I didn't know theaters still used film. I figured they were all digital." In response, I'm writing a brief article about digital cinema, and need an apples to apples comparison to cite.

Here's what I've found so far on the internets:

A) Standard DVD resolution is 720x480 = 345,600 bytes of data per frame
B) 345,600 * 24 frames per second = 8,294,400 per second
C) 8,294.400 * 60 seconds per minute = 497,664,000 per minute
D) 497,664,000 * 120 minutes (average movie length) = 59,719,680,000 bytes

So an uncompressed movie in DVD format is approx 60GB in size. MPEG 2 compression takes that down to between 4 to 9 gigabytes, which ensures the film will fit snuggly on a DVD

35mm film, on the other hand, is considered to be around 4096x4096 resolution, so using the same formula:

A) 4096x4096 = 16,777,216 bytes per frame
B) 16,777,216 * 24 frames per second = 402,653,184 bytes per second
C) 402,653,184 * 60 = 24,159,191,040 bytes per minute
D) 24,159,191,040 * 120 minutes = 2,899,102,924,800 bytes per movie

So we're looking at nearly 2.9 TERABYTES of uncompressed data that would be required for a feature length film to be played at 35mm quality. With a 10:1 compression ration, that only brings it down to ~290GB (roughly 31 DVDs worth of data). Until they come up with some amazing storage, or incredible compression utilities, film quality projection will remain out of reach.

Am I way off on these assumptions? Do I need to correct some figures? Is there anything else you might recommend to add fuel to my argument?

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Larry Myers
Master Film Handler

Posts: 371
From: Herndon, VA, USA
Registered: Jan 2001


 - posted 05-01-2006 06:05 PM      Profile for Larry Myers         Edit/Delete Post 
Yes that 16,777,216 is correct but it's not what you think. That figure is for a typical slow speed original negative 35mm movie image of about 100 line pairs per millmeter. What you see in the theater is about half to 1/4 of that in resolution with a typical high speed 4 gen print running around 50 to 25 lp/mm. So half the resolution the mb's go from 16mb to 4mb. Then half again it goes from 4mb to 1mb. As you can see, really not all that far off from a very good DVD.

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Dan Chilton
Expert Film Handler

Posts: 191
From: Springfield, MO
Registered: Mar 2004


 - posted 05-01-2006 06:16 PM      Profile for Dan Chilton   Author's Homepage   Email Dan Chilton   Send New Private Message       Edit/Delete Post 
But wouldn't d-cinema want to get as clear a picture as possible (i.e. the first gen print), and not aim for the lower generation prints?

Wait... I'm a little confused. Is "first gen" the stock that runs through the camera? The stuff that every additional print is made from?

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Bobby Henderson
"Ask me about Trajan."

Posts: 10540
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 05-01-2006 06:55 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
Dan, do yourself a favor and don't listen to Larry.

The "35mm is slightly better than a good DVD" claim is ridiculous. Even 1080 HDTV doens't compare favorably against film done right.

In acquiring digital imagery from original 4-perf 35mm negatives (or neg dupes, interpositives, etc.) the current de-facto 2K standard is a compromise. 4K is much better, but still doesn't squeeze out every last bit of detail. That's especially true when you are working with the original camera negative (but that is a risky practice).

The just above HD quality 2K standard endures because visual effects companies and digital intermediate posting houses can produce 2K material at ever faster and cheaper rates. Producing the material in 4K can quadruple the render time and data storage required. However, today's computer technology could handle 4K material faster and more efficiently than computers could handle 2K just 5 years ago.

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Larry Myers
Master Film Handler

Posts: 371
From: Herndon, VA, USA
Registered: Jan 2001


 - posted 05-01-2006 07:45 PM      Profile for Larry Myers         Edit/Delete Post 
This is how it goes with resolution.

Typical Sun Resolution on a nice summer day = 2000 lp/mm
Typical Bees Wax Candle resolution =1600 lp/mm
Typical Lens Resolution in summer sun = 500 lp/mm at f4
Typical slow speed stock that runs through the camera = 100 lp/mm
Typical EK Show Print = 80 lp/mm
Typical slow speed dup negative = 80 l/mm
Typical good quality high speed print = 50 lp/mm
Typical low quality high speed print = 25 lp/mm
Typical Eye Resolution at 10 inches = 8 lp/mm
Typical slightly out of focus picture = 4 lp/mm
Typical fuzzy image = 2 lp/mm

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Tristan Lane
Master Film Handler

Posts: 444
From: Nampa, Idaho
Registered: Feb 2002


 - posted 05-01-2006 08:02 PM      Profile for Tristan Lane   Email Tristan Lane   Send New Private Message       Edit/Delete Post 
Umm Larry.......... [Confused]

Wouldn't the resolution of real-world objects be determined by one's ability to percieve them?????

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Larry Myers
Master Film Handler

Posts: 371
From: Herndon, VA, USA
Registered: Jan 2001


 - posted 05-01-2006 08:52 PM      Profile for Larry Myers         Edit/Delete Post 
Exactly correct but then does a tree make a noise when it falls in a forest? The eye sees about 8 lp/mm. The sun runs about 2000 lp/mm. Xrays are around 10,000 lp/mm. The bottom line is the eye is not exactly the best detector. If you read about the discovery of DNA in 1952 you will sort of get the idea about image resolution and what is possible.

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Bobby Henderson
"Ask me about Trajan."

Posts: 10540
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 05-01-2006 09:12 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
Yawn... [sleep]

Trolls make me sleepy.
[Razz]

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Dan Chilton
Expert Film Handler

Posts: 191
From: Springfield, MO
Registered: Mar 2004


 - posted 05-01-2006 09:39 PM      Profile for Dan Chilton   Author's Homepage   Email Dan Chilton   Send New Private Message       Edit/Delete Post 
Now I'm really confused.

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David Stambaugh
Film God

Posts: 4007
From: Eugene, Oregon
Registered: Jan 2002


 - posted 05-01-2006 09:41 PM      Profile for David Stambaugh   Author's Homepage   Email David Stambaugh   Send New Private Message       Edit/Delete Post 
I still think ya gotta compare digital to "typical good 35mm release prints" and not camera negatives or showprints or anything else better than what theaters ever get.

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Monte L Fullmer
Film God

Posts: 8161
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 05-01-2006 11:03 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
[uhoh] yea..let's see if this topic of resolution can beat the record 725 posts of the previous blatter of "70vsDC" starring Mr. Myers..

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Frank Angel
Film God

Posts: 5116
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 05-01-2006 11:25 PM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
So let me get this straight -- we want to move to digital because....it can present an image that is barely as good as the worst that film can present in its worst-case scenaro. And that's fine with the industry? If this isn't a classic case of throwning out the baby with the bath water, I don't know what is. It would be much MUCH more sane, instead of discarding an entire existing infrastructure and replacing it with an entirely new system that is unproven and can easily be plagued with problems not yet discovered, yet has plenty of KNOWN issues, not the least of which is a cost in the billions that it would take to impliment such a radical technological conversion. And all this to get a result that cannot match what we know film is capable of with a minimum of investment. For example, how about slowing down the damn printers?!! Making EK Showprints would be a lot more cost-effective than moving to a questionable, unproven technology that we know even going into it has an inherent level of mediocrity.

Is there any question that theatres would find it a lot more cost effective to install media cleaners and a supply of Film Guard at each projector than having to install a $120,000 projector for each screen?

But then it's not about quality at all, is it. It's about getting the cheapest way to show the crap they churn out. If that's all that filmmakers think of their work, fine -- but how about just admitting it, and don't keep spewing that same self-delusional, bullshit about how good digital will look after the 10,000th play...yah as if anyone is going to want to see that soul-less trash after the first 3 weeks.

All I can say is, real filmmakers and cinematographers had better wise up, get off their asses and realize that unless they can live with the painful visual limitations of 2K digital, they had better step up to the plate and let their voices be heard. How come we haven't heard boo from the real filmmakers?

Look, we are only at the end run of the process from camera lens to screen, and we are seriously upset at the prospect of loosing the beauty of the film image, so you would think that the likes of a Vilmos Zsigmond or a Freddy Young would be out there with Uuzis mowing down studio executives. And where the hell is the ASC in all this? Surely they can't be taking this sitting down.

A plague on all their houses.

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Monte L Fullmer
Film God

Posts: 8161
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 05-01-2006 11:59 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
quote: Frank Angel
we want to move to digital because...
because of the "booth clowns" and "usher-Bees" that are ruining the 35mm presentations since the demise of the full time trained and skilled projectionist that were once hired by the theatre industry.

..Digital is a payoff for greed and this kills two birds with one stone: Giving the public the upmost perfect technology that the world is moving to and there is absolutely no high paid skill needed to run the digital machinery.

Also, digital is the answer from the losses by the circuits that have to issue refunds due to poor and interrupted presentations.

Circuits were losing money and prestigue due to these imperfections and have to recoup their losses with something that will contain all of these problems - and Digital seems to be the 'hero' in solving these problems.

..just my 3 cent comments on this..but not meant to be gospel.

-Monte

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Frank Angel
Film God

Posts: 5116
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 05-02-2006 12:51 AM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
Yeah, Monte, that's my point...sure there are problems with film presentation in its present state, most originating, as you point out, in shoddy theatre practices. But those problems are theatre-made and so they are theatre fixable -- they are not inherent in the film medium. And I contend that in the end, it would be less expensive for theatre owners to fix the degredation that THEY created than going willy-nilly into a new technology at an immense cost to them -- them being the same blokes who took 15 yrs to put in reverse scan reds. And if they don't address the basic problem of shoddy operations, what makes anyone think that they will not impose those substandard practices on the new technology?

Does anyone really think that digital will be immune to the idiot factor? Does anyone really think that yearly maintenance costs for a digital infrastucture will be cheap? Cheaper than film? Does anyone really think there will not be any lost shows with digital projectors? And let me tell you, there won't be a stable full of qualified tech personnel who are johnny-on-the-spot at your door in an hour and who actually know how to repair digital projectors and the computer network running them as there are techs who can rip apart a projector head and put it back together in time for the next show. With projectors, even if a head can't be fixed on site, there is likely a spare head down in the shop that can be swapped in and you're back on the screen. You think theatre owners will have spare $100,000 DLP heads laying around in the basement? Any idea how much a computer network technician gets per hour (don't forget to include travel time)? And the first time an upgrade from one rez nano-mirror module to the next has to be installed (oh...I forgot...you can't put a 4K module in a 2K head -- seems that backward compatible idea died with film), all that moeny the cheap theatre owner thought he was going to save by not having to hire trained film projectionists to run film, will be flushed right down the toilet. Hell, the money lost in electricl inefficiency of DLP alone would cover a trained projectionist (7000w to fill a 40ft screen with DLP while only 4000w is needed to do a fine job with film -- multiply THAT per hour per screen in a 20 screen multiplex).

I think that cost-wise, there will be a big awakening on the part of the those theatre owners/chains who buy into this.

And the last thing which I have asked over and over -- HOW DOES THE DLP MODULES AGE? What are the aging characteristics over time? Does it become more and more inefficient in terms of brightness or color purity? Do those nano-mirrors start to fail one by one leaving specks of color or black on the screen, which I contend would be much, MUCH worse than flecks of dirt or minor scratches which last all of a 24th of a second. Will those dead mirrors stay on or off through an entire movie?....which would pretty much debunk that whole idea about first to last "pristine" presentation.

I don't expect the hardware manufactures to volunteer this information, but I am stunned that theatre owners aren't demanding answers to questions that they certainly should be asking.

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Larry Myers
Master Film Handler

Posts: 371
From: Herndon, VA, USA
Registered: Jan 2001


 - posted 05-02-2006 07:35 AM      Profile for Larry Myers         Edit/Delete Post 
I know, people don't like all the numbers. Although I think it's like being at the race without knowing anything about MPH speed and Horsepower. So your in this race and you don't know what the numbers are or how good the other side may be and how bad your side may be.

It's kind of the American way. That's how we have been fighting wars lately. So when we get are asses kicked, we get real surprised.

[ 05-02-2006, 11:48 AM: Message edited by: Larry Myers ]

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