Wednesday, January 3, 2007

The Cons of Digital Projection

Digital projection is touted as a way to improve the presentation of movies. In fact, it only offers an improvement over presentations that are bad to begin with.

Digital projection is really about removing the costs of printing and shipping film, and about distributors having more control over exhibitors.

Picture Quality
35mm film offers higher resolution, color range, and contrast ratio than digital projection. (And 70MM is even better.)

However, most films today are digitally scanned during editing and post-production. Once they enter the digital realm, the resolution is of the movie is limited to the resolution of the scanned images. This means that any film prints produced will have roughly the same visual quality as digitally projected copies of the movie.

Note 1: Occasionally, films are digitally scanned for editing and then the edits are repeated on film. In these rare cases, projected film will have a greater resolution than digital. This is most likely to occur with movies without (m)any visual FX.

Note 2: I believe the picture quality of a digitally scanned film may be further degraded when digitally projected. I saw Star Wars: The Phantom Menace projected on film on a ~60' screen, and projected digitally on a 49' screen at Skywalker Ranch. I found the digital image to be noticeably inferior. I will concede that this was possibly due to the limitations of the earliest digital projectors.

Why do things like "resolution" or "contrast ratio" matter?
With low resolution, smooth lines can appear "jaggy." Small details are lost.

With a low contrast ratio, bright and dark areas may look correct, but in-between areas don't have as many "levels." Shadows can appear blocky.

More specific details are better espoused by more knowledgeable folks, but ultimately a better, sharper, more realistic-looking image is more likely to draw you into the fantasy of the movie.

Benefits of Digital Projection
Because there are no moving parts, digitally projected movies should always have a steady, rock-solid image that never accumulates dirt or scratches.

Projected film moves past the lens at a rate of 24 frames per second. Therefore, film projectors must be carefully maintained and operated to achieve a steady image. Jitter and weave are common problems with unprofessional 35mm presentations.

Also, film can accumulate dirt and become scratched in poorly operated venues.

That said, film is every bit as steady and clean as digital when operated properly, and digital projection can easily suffer from scratches or dirt on the lens, projection booth window, and screen.

Technological Advances: 2k? 4k?
The resolution of current digital projection is 2048 x 1080 pixels (source), often referred to as "2k." Next generation digital projection already in the works (4k), will have a resolution of 4096 x 1716. I expect it will be very difficult to determine which theatres are using which projectors.

The Costs
Digital projectors cost ~$100,000+ and may quickly become obsolete. A quality 35mm film projector costs ~$30,000 and lasts for decades.

The Dubious Future
Eventually, the technology for digital projection will advance to the point that the picture quality equals or even surpasses that of 35mm film. It is unlikely that cinemas which have invested in 2k projectors can afford upgrading to 4k, or whatever advances follow.

Theatres currently have a great deal of support for their expensive new equipment, and most digital movies are presented professionally. I fear that will change. Many cinemas are unable to operate simple film projectors correctly. Problems with the complicated computer equipment of digital projection may be worse.

Digital projection will not fix many of the problems that plague 35mm presentations in so many theatres, and drive away moviegoers. It will not prevent moviegoers from talking on their cell phones. It will not ensure that cinemas replace their bulbs when they grow dim. It will not prevent screens from being stained & scratched. It will not force employees to check the focus. It will not encourage the construction of larger screens. It will make it easier for cinemas to show commercials and for distributors to change the content of movies while in release.

The sad fact is that theatres could spend a tiny fraction of the cost of digital projectors to improve their current presentations by better training their staff and maintaining their equipment.

Digital projection seems here to stay. It is not difficult to imagine a future where many cinemas are forced out of business because of the high cost of digital projectors, coupled with decreasing attendance as more and more moviegoers stay home with their increasingly impressive home theatres.

But perhaps digital projection can co-exist with film. Just as there are fast-food outlets alongside 5-star restaurants, cinemas could operate both small digital auditoriums and special big screen auditoriums specializing in film, maybe even in 70MM.

This article has been rewritten, based on feedback from contributor Craig and the folks at Film-Tech. Any errors are mine, not theirs.

Additional information: WikiPedia: Digital Cinema


moviedood said...

One thing i never hear anyone mention is the frame rate at which the digital projectors are capable of. 24-30 frame rates are good, but some of these newer movies like Spiderman 3 need faster framerates. The first fight scene in Spiderman 3 was full of quick action, i couldn't see anything happening, it was just a blur. Im thinking if i saw the movie in digital it would look cleaner during these scenes. These projectors should be capable of doing a higher framerate like 40-50 fps. but i guess it all depends on the framerate in which the scene was taken at.

Anonymous said...

You say that you lose quality over 35mm, but I don get this logic as you already stated that the film gets scanned for digital processing (visual effects) which then gets rescanned to film. if the film was shot with a 35mm camera it should look cleaner and crisper on a DLP then a 35mm projection without any burns or scratchs. You are still going to get 35mm film effect (grain, resolution) you just aren't projecting it from a film roll. Most film isn't scanned higher than the traditional 2k resolution anyway. Unless you are comparing footage shot with a digital camera vs film shot on a 35mm, I don't see how you are getting less quality with DLP. I love the way it looks compared to 35mm. Its like watching HD tv compared to SD tv.

Jonesy said...

Yes, when 35mm films are scanned in at 2K for a digital intermediate, a great deal of image resolution is lost forever. In those cases, the resolution of a 35mm presentation will be very similar to that of a DLP presentation.

However, the DLP presentation will not have the same contrast ratio or color range of 35mm projection. That is "how you are getting less quality with DLP."

Digital intermediates are usually scanned at an anemic 2k resolution, but 4k is slowly becoming more common. 35mm prints struck from a 4k DI have almost the resolution of the original negative. (35mm film has an approximate resolution of 6k)

Of course, 4k digital projection is then a possibility, but here's the rub:

They WON'T be in 4k resolution at the thousands of theatres that have spent a fortune on 2k digital projectors.

And good luck finding a theatre that will advertise the resolution of their digital projector or the digital print they are displaying.

As for loving the look of DLP compared to 35mm, that is simply a subjective matter, and I cannot really respond. After all, a lot of people love McDonalds.


RiseDarthVader said...

I work at a cinema in Australia and in fact we are testing digital projection for all of Australian cinemas yet we still do go in during sessions and check from problems. Just because we don't check for focus any more doesn't mean we aren't checking at all.

Jonesy said...

That's great that you check for problems. Most theatres don't. :(

Why is your theatre switching to digital? If your theatre actually cares enough to send people in to check, you probably have a good presentation. Digital will only decrease the resolution, contrast ratio, & color depth.

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