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Author Topic: Image resolution of 35mm cinema film Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 02-23-2004 11:55 AM                     The SMPTE Journal, February 2004 issue, has an article regarding film resolution in a theatrical setting.To paraphrase the seven page article, they shot a custom resolution chart using industry standard cameras with Kodak stock; made wet gate answer prints and normal negative, IP, dupe negative and release prints on different printers and release print stock. In the negative stage the resolution was 2100L/Picture height, answer print = 1400L/PH, release print 1000L/PH. They projected the release prints in selected cinemas In the USA / Canada / France / Italy, the highest resolution was 875L/PH and the average was 715L/PH. In fairness they noted that higher resolution in the cinema is possible but they where looking for what today's filmgoers receive when they go to a typical, state of art, cinema.  |  IP: Logged Floyd Justin Newton Jedi Master Film Handler Posts: 559 From: Phoenix, Arizona, USA Registered: Jun 2002 posted 02-23-2004 12:22 PM                     Richard-- NOT very much, at least here When you have wannabe operators (children) in the booth who don't even know how to focus a picture on the screen. I don't worry about resolution or any thing else in the cinema today, considered the way they are run (ruined). fjn  |  IP: Logged Christian Appelt Jedi Master Film Handler Posts: 505 From: Frankfurt, Germany Registered: Dec 2001 posted 02-23-2004 01:30 PM                     Do you mean LINES or LINE PAIRS, which I know from many measuring procedures? That makes quite a difference, and 2100 LP from original negative comes close to the practical 4K resolution for 35mm scanning/recording. I believe that most of the original quality is lost in high speed mass printing AND improper duping (John P. has reminded us in numerous threads about the proper procedure which requires step printing at least once, and looking at the release patterns, I doubt that the studios really care about that extra image quality. So most of what is preserved during post production will be visible only for those few theatres that get EK or "grade A" prints, the rest of the world gets whatever can be produced cheaply. Many good films, i.e. THE LAST SAMURAI have been totally destroyed by improper release printing, that level of quality is enough to make people wait for DVD. An no amount of care on the exhibitor's side can make these prints look better or even good.  |  IP: Logged Larry Myers Master Film Handler Posts: 371 From: Herndon, VA, USA Registered: Jan 2001 posted 02-23-2004 01:37 PM                 Hi I am not sure what they mean by L/PH. Most film image resolutions are measured in Line Pairs per Millimeter or LP/MM or L/MM for short. A perfect f-1 lens in noon summer sun runs about 2000 l/mm center resolution. Most name brand still camera lens will do about 500 l/mm in noon summer sun center resolution. Most professional still images from slides with ASA speeds around 100 are about 75 l/mm. Typical 35mm release print resolutions I have seen run between 10 to 30 l/mm although some can go as high as 40. Old projection lenses (Kollmorgen) can actually be half the resolution as a new ISCO HD lens. Now add someone not focusing the projector and you have a real mix and match of presentation quality. Larry  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 02-23-2004 02:33 PM                     How do these findings affect the argument that dCinema's 2K resolution doesn't match 35mm?  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-23-2004 02:39 PM                        What format is this? Academy or scope will have greater resolution than 1.85, given the same screen height.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 02-23-2004 02:52 PM                     Lines per picture height based on a custom chart using sine wave patterns to permit more accurate MTF reading from each stage of the film process, from negative to projected image. The chart had a mid-gray background which also allow for more accurate evaluation of the image. Based on the chart set-up the maximum could equal 2400L/Picture Height; the chart was shot to resolve 2100L/PH to allow the more target wave patterns to be spread out on the image area to help in evaluations. Line pairs to check lenses, especially on a collimator is fine but the lines per picture height is a good guage to compare 35mm to a digital image. They noted that they tested the camera lenses and found that they dropped 25 - 30% from their maximum ( ideal resolution based on the focus / stop used. It appears that Academy was used ( there are a couple of sentences in the paper which are confusing ) with the 1.85 chart apparently cropped which yield the 2100L/PH. The projected screen evaluation was a 1.85 image......so true anamorphic would of course be better.  |  IP: Logged Larry Myers Master Film Handler Posts: 371 From: Herndon, VA, USA Registered: Jan 2001 posted 02-23-2004 03:09 PM                 Hi Image resolution has nothing to do with format. Really, the only imputs to image resolution or the ability to see detail, are the focal length of the camera, the distance to the subject and the type of film being used. This is a very hard concept to understand so I expect to get a little flack on this. Larry  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 02-23-2004 03:42 PM                     Larry...on the same page. The article is of course much more detailed regarding lenses, equipment, type of film stock, microdensitometer tests, use of different labs, original test film shot in L.A. and France to distill into a couple of paragraphs....  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 02-23-2004 03:58 PM                        Call me stupid, but I still haven`t understood if you are talking about lines or line pairs. Could you clear that up for me please?  |  IP: Logged Larry Myers Master Film Handler Posts: 371 From: Herndon, VA, USA Registered: Jan 2001 posted 02-23-2004 04:22 PM                 Hi Lines per millimeter is a unit of measurment much like dots per inch, miles per gallon and so on. It's a way of telling just how sharp an image can be. The eye sees about 8 lines per millimeter. At 4 lines per millimeter things start to look soft. At 16 lines per millimeter, things look very sharp. It's impossible for the unaided eye to see the difference in sharpness between 20 l/mm vs 40 l/mm unprojected motion picture film strip. Both will look very sharp to the eye yet when projected, they will look very different. Larry [ 02-23-2004, 05:52 PM: Message edited by: Larry Myers ]  |  IP: Logged Bobby Henderson "Ask me about Trajan." Posts: 10973 From: Lawton, OK, USA Registered: Apr 2001 posted 02-23-2004 05:47 PM                     Just to hairsplit, digital projection is not up to 2K standards --at least 2K is not representative of the installed base of digital projector systems. The 2K chips are just getting to market. And they apparently require entirely new projection systems for install to replace the more common 1.3K (1280 X 1024) DLP format. Anyway, the line pair figures would be easier to understand if they were broken down into numerical terms similar to pixel values for the frame, such as the 1280 X 1024 figure I quote for DLP.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 02-23-2004 06:23 PM                    I'm with Michael. "Lines" has no meaning (except in the video sense). They have to be talking line pairs--that is, a black line next to a white line. You can't have just lines. Black lines next to black lines? That's laughable. But it's important to get the terms right because if you're talking about a fixed number of pixels like with digital I believe the line pair resolution is going to be something less than half the number of pixels in that direction. Besides the terminology, I have two objections: Line pairs across the image or line pairs per mm of film is a function of what contrast level you are looking at, even when starting with pure black and pure white. Look at a test chart under a microscope you'll see that rez goes on and on at less and less contrast until it disappears into muck. If you are being given a fixed number like so many per mm then it means someone has decided for you that they are going to count this far and no farther. Yet in reality it may go on somewhat farther but at lesser contrast (less ability to distinguish between what was once a black line and a while line). I am guessing that digital goes to a certain point then just ends abruptly. But with film there is no abrupt end. That is why resolution is best described as a function where line pairs/mm (or across an image) is related to contrast level...you can see how it goes on and on but peters out into muck. Remember, that "function" means a graph...if you aren't shown a graph you aren't being told the whole story. The second objection is how the measurement is done. I tend to think that there is an integration over time which will penalize film projection for jitter in the projected image. It is my firm belief that human vision handles jitter without it penalizing the perceived resolution the way it does would if a camera photographs the screen and multiple frames in slightly different positions are combined into one for measuring purposes.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-23-2004 08:59 PM                     Image resolution is a factor of all of the above but magnific ation is the and stability is the bigest Native resolution ie what can be recorded on the film is one thing but what can be reproduced on the screen is the only number that realy counts  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-23-2004 09:23 PM                        Steve Kraus wrote: quote: I tend to think that there is an integration over time which will penalize film projection for jitter in the projected image. It is my firm belief that human vision handles jitter without it penalizing the perceived resolution the way it does would if a camera photographs the screen and multiple frames in slightly different positions are combined into one for measuring purposes. I agree. The eye / brain is very good at capturing the instantaneous fine detail, and perceiving the maximum sharpness. I have seen the high speed motion studies done almost 50 years ago by Kodak's Dr. Fred Kolb and more recently by the Kodak Enhanced Theatrical Experience team, and even in the presence of some jitter or focus instability, the human visual system compensates and captures the scene information. If it weren't so, even the real world would be a continual blur. Much can be done to optimize the projection system, and it is certainly possible to get more than 80 line pairs per millimeter resolution on the screen. Likewise, printer slippage and the means of controlling it have been known since the days of Mssrs. Bell and Howell. Steve is also right that there is more to perceived sharpness than simple resolution numbers. Kodak's Chuck Crane, Kelly Nelson, Bob Lamberts, and other researchers developed much of the science of measuring image sharpness using Modulation Transfer Function, and "cascaded" system MTF. They also developed sophisticated ways of quantifying perceived sharpness using weighting functions that were dependent on viewing distance (magnification) and human perceptual science.  |  IP: Logged

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