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Discussion Starter · #1 ·
what is the film resolution of a good Kodack print? 3500x2000?


Let's say 3Kx2K divided on a 70ft screen (29ft high): you get 2,955 "elements" per squared foot while you get, with an XGA DLP a,d 2.35 lens, on a 10ft screen, 18,724 "elements" per squared foot on a 10ft screen ( all data for a 2.35 format).


I mean, I'm starting to dislike large screens (60ft +) and prefer 40ft screesn for films, which increases the contrast, depth and resolution. I found PH quite washed out, undefined on the 70ft screen I saw it while really great on the 40ft screen I saw it the second time.


While the source material makes a huge difference ( we can only work with 720x360 at best, the rest of of XGA in pure 2.35 being pixels of the chips and not the source), I'm really starting to find film lacking the crispness and details we can find a on well calibrated, maximised CRT or DLP or LCD. And the contrast and depth of "our" devices (especially DLP, 3DLP and CRT of course is much prefered.


Of course, the naturalness (24p) and the sheer size has some appealing aspect but...


No ?


But what is the current standard resolution of film ?


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for cinema sound in your HT, use cinema speakers and cinema amps! unbeatable.


[This message has been edited by David600 (edited 06-04-2001).]


[This message has been edited by David600 (edited 06-04-2001).]
 

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The numbers that I've seen used for 35mm commercial theater prints is somewhere on the 1500x1200 range once you start accounting to multigenerational prints from the original negatives, post production, editing, and the finally the theater print from a high speed duplicator.


There are special prints that can be ordered at significant extra expense that are done using a slower more labor intensive process, but also produce better prints. The vast majority of theater prints are from high speed duplicators however.


Even if the very best prints are used there is still some decrease in perceived resolution due to the limited play that is necessary to allow the film to correctly run through the projector. This causes slight differences in the registration of the frame in the gate during projection which reduces the perceived resolution.


Other defects like faded prints, scratches, burns, etc. all degrade the quality of the print.


So, taking all of this into account, there is something to be said about a digital print. The first time you see it will be the same as the 100th time.
 

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Film is a very different medium to digital and as such resolution is (IMO) not quite definable in the same way and is a factor if the light and the film stock used....


For example film can be blown up without the pixelation issues to a far greater extent due to (again IM uneducated O) the more analogue nature of the photon / film reaction...


I do remember some discussion on a digital camera forum where some film advocates said that 'digital would never surpass film' which to my mind is a foolish argument given Moores law, and the counter argument to this estimated 35 MM camera film to have a approx resolution of 8 - 10 Megapixels... Something that easily could be in digital cameras within a 2 - 3 year timeframe...


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Discussion Starter · #4 ·
Hi guys


Yes, digital film will soon blow us away ( and not just on SHREK or TOY STORY http://www.avsforum.com/ubb/biggrin.gif ). here's a letter exchange quite interesting:
http://www.broadcastengineering.com/...04_letters.htm


Hollywood Cheats Movie Goers


Dear Larry,


I found your article quite interesting and you hit on a number of points we all need to become more aware of. I wonder, though, if there is not one more dimension to the actual achievable resolution in a film system.


You start off using 35mm film as a benchmark and state that the film, has a resolution which is about twice horizontally and twice vertically the two megapixel resolution of 1920x1080. You note that some in the film industry claim only 2K resolution (about two megapixels) for 35mm film. CBS, in a study a couple of years ago, seemed to come to the same conclusion. That indicates a difference of opinion between the film manufacturer, Kodak, and users over the resolution capability.


What about the limitations in the optics? Will camera and projector lenses tend lower resolution? If the film has a resolution capability an order higher than the optical systems will support, that would not be a bad thing, as it would render invisible minor grain imperfections in the film while still achieving the desired result.


Karl Black

Broadcast Technology Instructor

Harris Broadcast Systems


Karl:

There is no simple answer. We use 35mm film as the benchmark for digital cinema. Native film resolution is not dependent upon characteristics of the film camera lens nor the theatre projection lens, nor does it include the losses encountered when making an interpositive dupe negative and release print.


The film grains in modern motion picture film average around 3.5 microns. The 3.5-micron film grains are about 0.0001377 inches in size. If each film grain just touched each other you would have about an average of 5,987 film grains across a full aperture of 0.980 inches (24.89mm). We know that the film grains in the three-emulsion process are randomly spread and as more light photons arrive, more of these silver halide film grains are going to become exposed. The exposed film grains are then developed and replaced with the appropriate dyes during processing and dye clouds are formed where their density is proportional to the number of photons that strike the silver halide grains. If you photograph a chart made up of high contrast black and white lines, the theoretical maximum number of line pairs (black and white lines) that the film negative can resolve then is somewhere around 190 line pairs per millimeter (lp/mm). Experience and published documentation show that the film negative does resolve better than 85lp/mm. In other words, using 85lp/mm, the film negative can easily resolve more than 2000 horizontal lines in a "full aperture" film camera.


In order to scan a film of that resolution, the scanner must be capable of least 3000 samples of that image. The number of samples will be tied to the actual distance across the image and will have a spatial sampling rate measured in cycles per picture width or cycles per picture height (c/ph). For a 16:9 (1.78:1) aspect ratio then you would have to have a sample grid of about 3000x1687 pixels to equal the resolution of 35mm motion picture film. That’s a lot more than the two megapixels used for HDTV with its 1920x1080 sample grid.


Kodak claims that film resolution is equivalent to 4096 pixels, which is true if you measure from sprocket hole to sprocket hole across the film. However, the image does not go from sprocket hole to sprocket hole. It is slightly narrower to allow for a sound track. Most release prints are shown with apertures of only 0.825 inches (20.96mm) across. This is called Academy Aperture. Assuming no loss from making a print, this results in an image with a resolution of only 3562 x 2000. Notice that the 2000 is c/ph. This is where the often-quoted figure of 2000 lines comes from.


The CBS tests you mentioned tried to equate release print resolution and came up with similar data. It also included the losses from the printing, MTF of the projection system and included both lenses and the projector weave.


The optics definitely will lower the resolution of the image as will the printing of the IP dupe negative and release print. The goal for digital cinema shouldn’t be to reproduce what the theater patron now sees from a release print, but to show an image similar to what the producer and director see when viewing and approving the answer print in the lab.


Thanks for your inquiry.





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for cinema sound in your HT, use cinema speakers and cinema amps! unbeatable.
 

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Another item to consider is compression. Film is completely uncompressed, but high-resolution video must be heavily compressed. It's staggering to realize that film has an effective bandwidth of several gigabits per second http://www.avsforum.com/ubb/eek.gif ! Consider the following example:


4 megapixels/frame x 24 frames/second x 30 bits/pixel = 2.88 gigabits/second


Computer generated movies like Shrek and Dinosaur compress very nicely, since they have no noise, but live video, and especially film, can be difficult to compress, resulting in noticeable compression artifacts.


Dave
 

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"we can only work with 720x360 at best, the rest of of XGA in pure 2.35 being pixels of the chips and not the source"



You need to try buying a few Region 2 (or Region 4 Australian) DVDs, sunshine! 1024x576 is the source resolution of an anamorphic DVD here in Europe (1.85:1). Notice how nicely that fits an XGA projector, no scaling required. (OK, so strictly speaking there is some horizontal scaling as its anamorphic, but there is no vertical scaling, that's my point.)


It is foolish to assume that the consumer electronics products available in the US are better than those in the rest of the world. In fact the reverse is true.
 

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Quote:
Originally posted by inti

[BIt is foolish to assume that the consumer electronics products available in the US are better than those in the rest of the world. In fact the reverse is true. [/b]


Hmmm. Where is your HDTV? ;)
 

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Quote:
Originally posted by Mad Chemist




Hmmm. Where is your HDTV? ;)
Works just fine thanks :p (Well, if they would show more HD content and if some of networks would stop flogging 576P as HD and, oh, if my year old projector would actually handle [email protected] But, but we do have it... errr never mind :D )


Todd
 
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