Demystifying
Digital Cinema Part 3:
'Future-Proof': Myth Or Reality?
by Michael Karagosian
NATO Digital Cinema Consultant
The last
two articles (Part
1) (Part
2) in this series introduced the ideas of a “data
model” and a “broadcast model” in order to
compare their features. The second of those articles suggested
that those working with digital cinema might find greater
economic advantages by borrowing from the data world rather
than from the broadcast world.
Now that we have at least one good idea in our pocket for
reducing system cost, let’s explore the idea of making
our system “future-proof.”
One of
the most debated aspects of digital cinema today is the quality
level required. With film, the concept of quality has been
simple – deliver the best image you can within the allotted
space on the film frame.
Unfortunately
for film systems, “the best you can” is not always
the “best we wish it could be.” Film systems are
inherently analog in nature, and high-volume replication of
movies does not readily deliver the same quality of picture
captured by the cinematographer.
One of
the touted advantages of digital systems is that they do not
inherently introduce a loss in quality when copies are made.
In fact, it is well within the technology to have lossless
quality in distribution. It would appear to follow that digital
distribution is the cinematographer’s dream come true
– giving the cinematographer the potential to deliver
to our theatres the exact images that they capture.
Ideally,
this is true. But in our less-than-ideal real world, some
compromises are made. These compromises are due largely to
the limitation of today’s technology, and manifest themselves
in terms of limited resolution, limited color space and quality
limitations introduced by reformatting and compressing the
data. These limitations can be overcome, but at a price. Thus,
high quality has a cost associated with it, and is not inherent,
after all, in our digital cinema systems.
All of
this sparks the debate consuming Hollywood of late: “Is
digital cinema technology good enough to implement widely
today, or should we wait to implement improved technology
at a later date?” This question can be reframed as, “Does
digital cinema only need to replicate the level of quality
that we see with celluloid today, or should the goal of digital
cinema should be to distribute the best that is possible?”
Ideally,
wouldn’t it be nice if we could separate the issues of
distribution quality from those of the display quality allowed
by our cinema system? In other words, we would like to allow
our system to accommodate the more technologically sophisticated
content a studio might deliver at any point in the future.
The system may not be able to reproduce the full quality intended
when receiving this more sophisticated content, but it would
display the movie to the best of its ability. As it turns
out, this isn’t such a fanciful idea.
The video
projector world already has the “resizing” feature,
which allows a projector to reformat incoming video to match
the native capability of the projector. By “native,”
we mean the inherent technology that the projector is based
upon. The native technology introduces limitations in terms
of resolution, color, brightness and contrast. The job of
the resizer is to reformat the incoming video so it can be
displayed at its best given the native technology of the projector.
Today’s
digital cinema projectors also incorporate resizers. The native
resolution of installed projectors is currently 1280 x 1024,
but in practice, digital movies are commonly delivered with
a resolution of 1920 x 1080, higher than that of the projector.
(In the future, even higher resolution images may be delivered.)
The projector displays the higher resolution image by resizing
the image to match its native resolution.
Resizing
is an important part of the digital cinema projection process.
It introduces a degree of flexibility that makes it somewhat
future-proof. Note the “somewhat.” If we should
want to send the projector an image that is larger than what
the resizer can support, then we’re out of luck. It then
becomes time to buy a new projector.
Obviously, we want to mitigate if not eliminate the issue
of having to buy a new system whenever the digital format
changes. There are several ways to accomplish this. One is
to use the broadcast-style server and resize the image so
it can be sent to the projector (Figure
1). This method can accommodate a variety of projectors,
each requiring images to be in a specific and different format.
But with this “broadcast” model, the projectors
may not be interchangeable, i.e., one may not be able to move
the projector from one auditorium to another.
Another
method is to look into our crystal ball and implement a projector
that can accommodate the likeliest higher-resolution future
formats. This can work for both broadcast and data models
but, as we addressed in the prior article of this series,
the “data model” (Figure
2) offers a more cost-effective approach. There
are other very compelling methods for making the server-projector
system future-proof; all are “data model” variants,
but we’ll forego detailed descriptions of these so as
not to lengthen an already lengthy column.
We should
keep in mind that there are several goals for future-proof
systems. To compete with ever-evolving home entertainment
technology, we need to allow for eventual quality improvements
– but we want these improvements to be backwards-compatible
so as not to obsolete older equipment. The concept of “future-proofing”
is also compelling in that it becomes an enabling factor in
achieving “single-inventory movie content” (movies
distributed in a single format that all digital cinema systems
can utilize), which will be of benefit to both exhibitors
and distributors. Altogether, that’s a tall order to
fill, but one that’s certainly worth pursuing.
