When someone inquires about a 4K display, what are they
talking about? Sure, 4K, but what does that mean exactly? Does 4K mean the same
thing for flat panels and projectors and screens?
Since the development of 4K we’ve seen a lot of confusion
among our clients and their customers over this very question, especially when
we ask them, “Which 4K?”
Draper consultant relations manager Steve Cook is here to
clear up that confusion, and explain why we have to ask, “Which 4K?”
By Steve Cook
4K has gotten very confusing for many people, because over
time different ‘types’ have been introduced.
How it all started.
The original 4K came from the movie industry. When digital projectors first began replacing movie theatre film projectors, they were 2K. Their resolution was 2048 x 1080, so 2K actually meant “more than 2000 pixels wide.”
4K projectors began to replace 2K in theatres. Their resolution was 4096 x 2160. This 4K format created by DCI (Digital Cinema Initiative—4K DCI) meant they were “more than 4000 pixels wide.”
Both 2K and 4K theater grade projectors had an aspect ratio
of 1.9:1 (or more precisely, 1.8963:1 for the 4K resolution of 4096/2160).
However, over 90% of modern movies are in 2.39:1 (Scope)
format. To deal with this, a 1.26x anamorphic lens would be placed in front of
the regular lens to stretch 1.9:1 to 2.39:1 (1.9 X 1.26=2.39).
The coming of “4K.”
Things got a bit more confusing when flat panel companies started making their displays twice the resolution of the then-current 16:9 1080p TV. Twice the resolution of 1920 x 1080 is 3840 x 2160 (2160p).
Because the vertical resolution was the same as the movie theater
4K format, manufacturers referred to their displays as “4K.”
These displays are not the same resolution or aspect ratio as theater grade 4K projectors, and their horizontal resolution is not “more than 4000 pixels wide.” They are only 3840 pixels wide.
To help differentiate the two 4K resolutions, display
manufacturers began referring to 4K TVs as 4K-UHD (Ultra HD). 4K theater grade
projectors are referred to as 4K-DCI (Digital Cinema Initiative).
But what about projection?
This brings us to where things have gotten confusing for screen users and even some dealers. As a screen company, we have to ask “which one” when someone asks about 4K because of the multiple aspect ratios. That’s because projector manufacturers have joined the flat panel companies and introduced 4K-UHD projectors.
There are projector manufacturers who make projectors with 4K/4096 x 2160 resolution, which is the same as theater grade projectors used for 4K-DCI, but not for use in commercial movie theaters. Instead, they are marketed into home theater, simulation, and other commercial applications.
So now that projector companies are making 4K-UHD, 4K/2160 x
4096 resolution models, and 4K-DCI theater grade models, it is more important
than ever to know “which 4K” you are buying.
How can I tell which resolution and aspect ratio I’m dealing with?
The first step is to find the “native resolution” noted in the projector specifications. Ignore the “compatible resolution/s” because that just means it will display those resolutions. Native resolution tells you the resolution and shape/aspect ratio of the chip/s inside the projector whether it is using LCD, LCOS, or DLP technology.
If the native resolution is 3840 x 2160, divide 3840 by 2160.
The answer is 1.778, which is also a 16:9 aspect ratio.
If the native resolution is 4096 x 2160, divide 4096 by 2160
and you get 1.8963:1. That rounds up to a 1.9:1 aspect ratio.
But what about Scope?
As mentioned earlier, over 90% of movies are Scope (2.39:1). The catch? There are no 2.39:1 projectors. However, you can use a 2.39:1 screen with any projector that is 16:9 projector or that is native 1.9:1.
If the projector model has “lens memory,” it can store
multiple zoom/shift settings to make the image larger or smaller to fit all
content onto the screen at a constant height.
The other way is to use an anamorphic lens in front of the
regular lens. There are a couple of downsides to going this route. First of
all, the lens typically has to be moved into place for Scope content, then
moved away when projecting non-Scope content. And while anamorphic lenses are available
for the home theater and movie theater market, they can be expensive. Anamorphic
lenses for theater grade 4K-DCI projectors can cost up to $15,000.
The end result.
4K offers a better-than-ever viewing experience, as long as you are using the proper display tools. Figuring out the exact “4K” resolution and format are important steps in making sure you get the most out of the experience.
Source: Blog Posts