How are cinema-grade projectors / film techniques different from others?

Question

I was curious about how these projectors are able to project images up to these huge displays with such a crisp and high-quality definition. What resolutions are these films being filmed / played at? These are the questions I have lol

Thanks!

In: Technology

Answer 1

I’m not a projectionist but I’ve spoken with some people who work with these projectors, and while I don’t fully understand much of it I can give you a rough idea of how projectors work in modern cinemas.

Most cinemas have transitioned to digital projectors many years ago (with the exception of true IMAX and other special film formats). They’re huge, extremely expensive projectors with water cooling and a server that goes with it. The server contains the DCP which is a huge and complex file structure that contains the image and sound data. The projectors usually have a 1998 x 1080 resolution (called “2K” with a 1:1.85 ratio) and a bit depth of 10, though some bigger cinemas are starting to buy 4K projectors, and I imagine that soon it will become the norm. But transitioning to 4K isn’t cheap so smaller cinemas are holding onto their 2K systems. Especially with smaller screens in smaller rooms, 2K works fine and the benefit of 4K won’t be very obvious unless you’re in the very front rows (which sucks anyway).

The most obvious difference between cinema projectors and what you’d get for your home is the light output. The further away the screen is, the bigger the image can get, but the more light you will need. This however produces a LOT of heat and needs a lot of cooling. The bulbs are incredibly expensive and have a limited life span, so smaller cinemas usually dial down the bulb brightness to save some costs and extend the life of the bulb. But this of course results in a duller image. I guess there are regulations in place to prevent cinemas from doing this as distributers want to have control over the experience, but I’ve heard it’s common practice to dim the bulb.

So all in all, the resolution of these projectors is nothing fancy, but of course they have better optics and the projection screen itself is much more reflective (it has little shiny specs inside that help it reflect more light towards the audience but not towards the side). This allows the room to be darker while the screen is brighter. Combine this with high bit-depth images with no visible compression, good quality color reproduction, a ton of light, and you get a very clean looking image.