How much more resolution does a movie theater "picture" or view give you than HDTV?

Dave H

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Just curious.

When I go to the movie theater to watch a film, how much more resoultion (if any) am I getting than a 1080 HD signal?
 

Jack Briggs

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Yes, David is correct here. There's no true way to measure the horizontal resolution of film, but it's often said to be at around 6,000 lines.

However, most prints are not of the highest quality (to be expected from high-speed duplication). Couple that with the less-than-perfect projection facilities at most commercial cinemas, then HD home-video sources effectively close the gap. Even state-of-the-art DVDs, when viewed on a high-end home-theater display, come alarmingly close in image quality to what you see at the local gigaplex.
 

jeff lam

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From my experiences, I actually like the look of HDTV better. To me, it looks more like I'm looking out the window than looking at a screen. I don't get that at the theater. I was just at the theater last night too.
 

Christian Behrens

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I just read a report about current digital cinema, and amazingly it looks nearly like HDTV. The industry is working towards a standard now (there isn't one yet) which offers a resolution of 1080 lines with 1920 pixels each, 24 frames per second.

-Christian
 

Dave H

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Now what about Star Wars being shown digitally. Will I see more resoultion this way?

My friend claims it will look no different than seeing it the standard way at the theater. I think he is wrong.
 

Mark Turetsky

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Star Wars will look better digitally, because it was shot in a digital medium. In order to show it on film, it needs to be transferred to an analog medium, thereby bringing it one generation away from the digital source.

As for the resolution of 35mm film, I can only speak for still photography, because that's my forte. It depends on the film: Kodak's technical pan film can usually resolve images to the point where image resolution is limited by the lens you're using and the motion of the shutter, or any small vibrations within the camera. However, I don't think you'll ever see any movie being shot on technical pan. The claim at Kodak is that tech pan can resolve 125-320 lines/mm. I don't know what the size of a motion picture negative is (it's smaller than a still neg), but a still negative shot on tech pan would be roughly (at it's low end) (24mm x 125 l/mm) x (36mm x 125 l/mm) = 3000 lines by 4500 lines. Now, once again, you will not see movies shot on this stock. (Just for curiosity's sake, at its high end you'd get 7680 x 11520 lines). That is about the upper limit you can get on 35mm film right now. Now, in reality, movies aren't going to be shot on tech pan because A)it's a black and white film B)It's a very slow film (25 ASA) and would therefore require very very bright lights to register C) it's a bitch to develop (Kodak has very specific instructions about developing it, which differ from other films. Heck, it's even got its own special developer, technidol).

So then, let's move into a fine grained color film area, with a moderate speed. Let's say Fuji Velvia, which will resolve at a maximum of 120 lines/mm. Well, that's not much lower than tech pan at its low end (2880 x 4320).

Remember as well: this is only 35mm we're dealing with... Imax creates a much much bigger reel of film than 35mm, as does 70mm.
 

Mark Turetsky

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I made a mistake in my math. The resolution of film would actually be double what I said, since the ability for film to resolve lines is measured in how many black lines it will resolve from a lens chart, so therefore the film would resolve a black line, then a white line, then a black line, then a white line etc. so it would take twice as many pixels to resolve.
 

Dave H

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Thanks for the info. His reasoning was that since it's being projected on to a screen instead of a direct view digital monitor, if you will, it won't matter.
 

JohnRice

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Mark,

Actually, there is still a bit of a fault with your logic. The main reason is that film is still organic and digital isn't. I don't think it is really proper to call film "analog." Since film is organic, those lines can be placed pretty much anywhere and they will be reproduced consistently. Since digital has a distinct "on or off," making minute shifts between the image and the digital receptor will severely affect the image. So there needs to be a minimum of three pixels per line/mm of resolution of film and as many as five pixels per l/mm. Also, a movie frame is usually 24x16, not 24x36. Remember, movie film travels vertically, still photography film moves horizontally.

At the minimum three, this makes a 4,800 x 7,200 image using a 100 l/mm film as the standard. Of course, if you are talking anamorphic, that is a concept that kind of goes out the window with digital sinced you are no longer dealing with a physical media you are trying to fit to the screen. Once you are projecting the image, an important thing is to use some sort of subtle softening (like Gaussian Blur, for you photoshop folks) with optics to cover up the individual pixels. I know there are accessory lenses for home projection units that do this. After all, film doesn't have "pixels" in the same sense as digital.
 

Mark Turetsky

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John,

Good point about the ability to place those lines anywhere on a piece of film, I hadn't thought of that. But it makes sense though, since lines/mm measurements refer more to the size of the line to be resolved, rather than a pixel by pixel resolution.
 

Jeff Kleist

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My friend, who's done digital effects for films like Spider-Man says that 35mm film is 2000x2000(2K) pixels, though they frequently render in 4000x4000(4K) because of how things process. I'm not suprised that they work in 4K for restoration,as you need to be able to see all the detail
 

Mark Turetsky

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There's another piece we're not talking about with regards to digital: noise. In order to be used under certain light conditions, the picture needs to be punched up to a higher luminance, creating the digital equivalent of film grain: noise. For example, if you take your camcorder into a low light situation, the result will look grainy, even though there's no film grain involved in the process. What you're seeing is digital noise. Of course, when using higher speed film, you tend to get more grain. What this all boils down to is that you can't definitively say "film has such and such resolution and digital has such and such" because there are so many variables which need to be taken into account.
 

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