This is topic Resolution equivalent for 35mm in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.


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Posted by Dan Chilton (Member # 2288) on 05-01-2006, 04:30 PM:
 
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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Posted by Larry Myers (Member # 738) on 05-01-2006, 06:05 PM:
 
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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Posted by Dan Chilton (Member # 2288) on 05-01-2006, 06:16 PM:
 
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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Posted by Bobby Henderson (Member # 840) on 05-01-2006, 06:55 PM:
 
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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Posted by Larry Myers (Member # 738) on 05-01-2006, 07:45 PM:
 
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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Posted by Tristan Lane (Member # 1169) on 05-01-2006, 08:02 PM:
 
Umm Larry..........

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

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Posted by Larry Myers (Member # 738) on 05-01-2006, 08:52 PM:
 
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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Posted by Bobby Henderson (Member # 840) on 05-01-2006, 09:12 PM:
 
Yawn...

Trolls make me sleepy.

 

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Posted by Dan Chilton (Member # 2288) on 05-01-2006, 09:39 PM:
 
Now I'm really confused.
 

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Posted by David Stambaugh (Member # 1102) on 05-01-2006, 09:41 PM:
 
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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Posted by Monte L Fullmer (Member # 2797) on 05-01-2006, 11:03 PM:
 
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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Posted by Frank Angel (Member # 248) on 05-01-2006, 11:25 PM:
 
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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Posted by Monte L Fullmer (Member # 2797) on 05-01-2006, 11:59 PM:
 

quote: Frank Angel

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we want to move to digital because...

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quote: Larry Myers

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As you can see, really not all that far off from a very good DVD.

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Well, I've seen "very good DVDs" projected on a big screen, and typical 35mm release prints projected on the same screen, and the film easily wins that contest.

There was pretty clear industry consensus that the original 1280 x 1024 pixel Digital Cinema System introduced seven years ago did not have sufficient resolution to support viewing distances as close as a 35mm print. There's a reason that Digital Cinema had to move up to 2K and even 4K resolution. So to say a "very good DVD" can match a 35mm print is ludicrous.
 

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Posted by Mitchell Dvoskin (Member # 751) on 05-02-2006, 08:53 AM:
 
These threads remind me of the old proverb, "Some people use statistics like a drunk uses a lamp post, for support rather than illumination".

If the "numbers" don't match what we are seeing, then the numbers are not giving us a meaningful scale to measure by. In that case, we need to re-evaluate how these numbers are obtained and what numbers are really meaningful.

Also, resolution is only one component of what make a good picture. There is also grey scale and color depth, which I don't see anyone talking about.
 

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Posted by Josh Jones (Member # 447) on 05-02-2006, 09:13 AM:
 
here here
 

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Posted by Larry Myers (Member # 738) on 05-02-2006, 11:45 AM:
 
Projecting a DVD on a large screen is not what I had in mind. From my point of view, which I think I share with many other photo engineers working on Digital. Viewing something 80 ft wide at 80 ft is exactly the same as viewing something 8 feet wide at 8 ft and is the same as viewing something .8 feet or 9.6 inches wide at 9.6 inches. This is all with 10 inches being the standard view distance from a printed page at 8 lp/mm. Thus the DVD comment.
 

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Posted by John Pytlak (Member # 331) on 05-02-2006, 12:13 PM:
 
Whether you are looking at the image forty feet from a 20 x 37 foot screen, or 40 inches from a 20 x 37 inch monitor, the SD DVD has less resolution than a 35mm release print or a 2K digital cinema image.

Maybe it's time to get new glasses for your far-vision.
 

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Posted by Larry Myers (Member # 738) on 05-02-2006, 01:23 PM:
 
All the eye needs is 8 lp/mm. Actually the range is from about 6 to 12. Anything more and it's thrown away. Now all that is needed is to work out the math. If you don't like the math, another way to see this is to get close up to a billboard. If you do, you will notice how fuzzy these billboards can be. Yet they look sharp from the highway. That is because the reduction ratio of 1000 ft vs 1 foot increases viewed resolution from less then .01 lp/mm to 10 lp/mm.

That why theaters are getting their asses kicked. It's viewing a high quality DVD's on a 3 foot wide HDTV using progressive scan anamorphic. The results look damn good at 3 feet away. Plus you get 5.1 sound to boot.
 

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Posted by Scott Norwood (Member # 30) on 05-02-2006, 02:33 PM:
 
The issue with DVDs isn't just resolution, but also compression artifacts. For some reason, this seems to be less of a problem with newer disks, but I defy anyone to sit through an entire movie on DVD without seeing objectionable MPEG artifacts. Also, see the post above about color space, contrast ratio, etc.

Anyway, there are basically three reasons why people go to movie theatres: to see material that is otherwise unavailable, to see film projected with better picture and sound quality than is available elsewhere, and for the social experience of seeing the films with a large group. Theatres aren't just suffering due to poor presentation quality, but also because there haven't been many good movies released lately (which results in less desire to see the titles which actually get released) and because the social experience has been steadily declining due to cell phones, rude patrons, rude theatre staff, etc.
 

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Posted by Larry Myers (Member # 738) on 05-02-2006, 02:53 PM:
 
Again don't get me wrong. I also like film. Yes, I can see resolution differences between film and a DVD. My point is most people can't. What differences do I notice? Lets take Moulin Rouge. The Kodak Vision stock film looks great. Very sharp. On one long stage shot you can see a guy with a flute wondering around like he doesn't know where he is going. You can clearly see the flute and as you look at him you ask yourself where is he going as he heads off stage.

On the DVD you don't see him at all much less the flute. But then again, on a 8 foot wide screen he is only 2 inches tall. On the other hand, in close-ups, the actors skin tones and highlights look every bit as good in both the DVD and film. With film it's on a 8 foot screen viewed at 8 feet away and the DVD is on a 3 foot HDTV viewed at 3 feet. Maybe it's my old eyes but both are damn close.

[ 05-02-2006, 04:17 PM: Message edited by: Larry Myers ]
 

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Posted by Monte L Fullmer (Member # 2797) on 05-02-2006, 03:29 PM:
 

quote: Dan Chilton

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Am I way off on these assumptions?

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quote: Scott Norwood

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I defy anyone to sit through an entire movie on DVD without seeing objectionable MPEG artifacts

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I almost never notice any MPEG compression artifacts on DVDs. Not saying they're not there, just that I don't notice them. Edge & detail enhancement are a different issue but I don't think they're related to compression.

I definitely DO notice compression artifacts on HDTV though. NBC seems to be the worst, at least judging from what the Eugene NBC affiliate is sending out.
 

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Posted by Monte L Fullmer (Member # 2797) on 05-02-2006, 04:17 PM:
 
course, we have to realize that DVD's uses the MPEG2 compression - which has a larger filesize rate due to the increased resolution than the more common MPEG which can only hold much smaller resolutions, yet also yields smaller filesizes.

Satellite TV services uses the MPEG2 format for transmissions of video signals.
 

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Posted by Bobby Henderson (Member # 840) on 05-02-2006, 05:44 PM:
 


I still say Larry is trolling.

He keeps repeating the same crappy half-truths, spun numbers and all sorts of oddities. HE IS NOT LISTENING TO ANYBODY, no matter how hard anyone tries to reason with him. You can clearly refute what he says, and he'll come right back and repeat the same garbage a few pages later.

Like I said:
 

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Posted by Dan Chilton (Member # 2288) on 05-02-2006, 05:46 PM:
 

quote: Monte L Fullmer

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Most digital film releases comes on a HDD where the files are actual raw uncompressed video data...of 300 to 700 Gb's.

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quote: Dan Chilton

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So are these digital films then shown on a 2K projector?

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quote: Aaron Haney

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Resolution of film: As demonstrated above, viewers need more than 2K. 4K will meet the requirements, with a little extra headroom. EFilm has a page talking about 4K digital intermediates which also discusses the size of the data

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Not exactly true. You will need more like 8k to exceed what the eye can resolve at that distance. Per the Nyquist theory, you need to oversample at 2x. In other words, for the system to display 3600 pixels worth of detail, you actually need 7200 pixels.

IMHO, based on what I've seen of 2k digital projection and film done right and wrong, 4k digital cinema at the same color depth and contrast available from the 2k DLP projectors will exceed the quality of 35mm film. 2k comes closer to film done right than you would think but it does not equal or exceed the quality of 35mm film. Of course, the industry is about to roll out 10's of thousands of 2k projectors instead of demanding 4k. 4k would give the studios the electronic distribution that they want while giving exibitors a clearly superior picture to home HDTV. I guess it makes too much sense.
 

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Posted by Larry Myers (Member # 738) on 05-03-2006, 09:57 AM:
 
If you want to use the subtend math, you forgot about the degrees of forgiveness. Even in the Circle of Confusion calculations, there is a degree of forgivness.

I like my eye resolution tables because the eye more or less resolves 8 lp/mm at any distance. Only the scale controls what the eye actually sees.

Example

1 lp/mm very fuzzy image
2 lp/mm fuzzy image
4 lp/mm slighty fuzzy image
8 lp/mm sharp image
16 lp/mm very sharp image
32 lp/mm very very sharp image.

The human eye can select all these images and put them in order even though the eye sees only 8 lp/mm. This is the area of forgivness. In other words, if pictures from about 3 lp/mm to 32 lp/mm are shown one by one, the untrained eye can't tell which one is which. If you look at them all together, in less the 5 seconds you can put them in order.

What does this mean. Well it means that watching a DVD on it's own at about 3 lp/mm will look about the same as watching a 7 to 9 lp/mm 35mm film presentation if both these presentations are in different rooms. Now put the presentations side by side and bam, you see the difference. Split them apart again and you don't. Lots of scientific studies have been done on this sharpness and degrees of forgiveness issues in the last 100 years.
 

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Posted by Eric Robinson (Member # 2966) on 05-03-2006, 02:46 PM:
 
Just curious, do cinematographers use film in their cameras or do they use digital cameras?

If they use digital cameras, then one couldn't expect to have film quality any greater than its origin?
 

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Posted by John Hawkinson (Member # 1135) on 05-03-2006, 03:18 PM:
 
The vast majority of features originate on FILM. Digital origination is an area where technology is clearly much less mature, and it's very hard for digital to capture the same breadth of light levels that you can capture with film.

Moving back to projection:
I continue to think that the pro-film people on this site overstate the case for film, and cannot see the future coming. Despite being a pro-film person myself, I find the pro-digital argument of "no scratches" to be extremely compelling.

The fact that it is possible to present film without scratches is not the issue. The reality is that most presentations are poor, and that most film prints do get scratched, and it happens apallingly near to the start of their run. You can fix this with digital, and you can fix this by reeducating the operators. But guess which one of those is never going to happen?

We then get the question of whether a 1024x768 compressed digital presentation is better or worse than some number of green or black lines. This is subjective, but, well...

--jhawk
 

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Posted by Mike Schindler (Member # 1309) on 05-03-2006, 08:20 PM:
 
I don't really know what all those numbers in the previous posts mean, but aren't most release print stocks of a higher resolution than the original negative? I'm guessing that this is also true for 2K video since you can typically see a film's grain structure in DLP. Also, on a typical 2K setup, how does the size of a single pixel compare to a perf in the screen?

I guess my thinking is that at some point these differences become so minute that other factors become more relevant. I don't think that scratches or dirt are much of an issue, because these things are easily prevented. But what about other things like focus, framing, jumping, weaving, ghosting, keystoning and all those other "ings"? I've never seen any of these problems in a DLP presentation, but it's rare to not see at least a few of them on film.

I live in Chicago, which apparently is the worst place in the country to see a movie, but the last film I saw at a theater that wasn't my own had no digital sound (although both the theater and print were equipped), the lens was too short so the image was being cropped on all sides, and it was out of frame so the titles at the bottom of the screen were partially cut off.

A few months ago, a coworker and I were watching the CARS trailer in DLP, and after it ended he turned to me and said, "Boy. Do you remember when we thought that film looked good?" But he's right. Despite number crunching, I've come to terms with the fact that DLP is better than 35mm for all these other reasons. And I'm OK with that. That being said, this week we open M:i:III in both 35mm and DLP. This movie was shot in anamorphic, and the print will be playing in our best auditorium. So I guess this will be the ultimate test.
 

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Posted by Patrick de Groot (Member # 858) on 05-05-2006, 12:27 PM:
 
Mike, what about posting your results of your comparison of a 35mm film and DLP video show of M:i:III?
 

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Posted by Tim Reed (Member # 137) on 05-05-2006, 02:34 PM:
 
Guys, like it or not, DC is happening. It's happening now. And it's not going to go away. Just like when we were forced to deal with polyester print stocks industry-wide, NATO wants it so NATO is getting it. Forthwith.

The technical arguments are really moot at this juncture. DC will only be improved upon, like sound was, like color was, etc., etc... And it seems film never was perfected, anyway. Kodak, for example, keeps coming out with improvements. ( John!)

As far as saying goodbye to old friends, does anyone care to recall which gave a better light; carbon arc or xenon? Xenon was clearly inferior and more dangerous, yet that didn't stop it from becoming boss in a few short years.
 

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Posted by Mike Schindler (Member # 1309) on 05-05-2006, 02:41 PM:
 
OK, I've watched both versions all the way through, and have run back and forth between the two over the course of the morning to compare certain scenes where I thought one or the other had some sort of deficiency. Here's what I've noticed. Trying to disregard any limitations imposed by the equipment we're using, it seems that there isn't much of a difference between the two. The DLP image is slightly sharper. The 35mm image has a little more detail in dark areas. The one place where DLP is much better than 35mm is color saturation. This surprised me quite a bit. It was most noticeable during explosions. It's very very evident throughout the SUPERMAN RETURNS trailer, but that looks better in DLP all the way around (which makes sense, since it was shot in HD).

So, yeah. Not much difference between the two, although I would like to hear other people's observations, because who knows what impact the equipment had on the comparison.

And speaking of the equipment, like I said before, in the real world DLP wins every time. Film jitters, anamorphic lenses are evil, etc. These are minor problems, but DLP doesn't have them. And it's ridiculous how much control the operator has over a DLP image, down to the pixel. So I'd go with DLP. But you could argue it's just a different aesthetic, and that's cool too. I'm glad that the choice is out there.
 

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Posted by Monte L Fullmer (Member # 2797) on 05-06-2006, 02:55 AM:
 

quote: Tim Reed

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As far as saying goodbye to old friends, does anyone care to recall which gave a better light; carbon arc or xenon? Xenon was clearly inferior and more dangerous, yet that didn't stop it from becoming boss in a few short years.

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