AmericanCinematographer201201

◗ Go with the Flow
This diagram shows how the Image Interchange Framework-Academy Color Encoding Specification,
better known as IIF-ACES, functions with three different capture devices.
struggle to move toward file-based
workflows on the post houses themselves,”
Cioni declares. “It’s not that the
crews on set are resistant to it, or that
the cinematographers can’t get a goodlooking
image out of it. In fact, workflow
problems usually do not occur on
set, but in post. It’s the post house that
is slow to upgrade and change. For some
facilities, getting a file-based workflow
[going] is like sucking a golf ball
through a garden hose, but they will
throw time, manpower and horsepower
at a problem, and if they apply enough
suction, they will get that golf ball all of
the way through. Or, instead, they could
just invest in a separate pipeline right
next to that one that is twice as wide!”
Restructuring an entire post
house’s pipeline can be a massive undertaking,
especially if that pipeline is based
on legacy standards. “For a digitally
captured production to look its best, and
to get the most out of the camera, an
all-digital path is the best way to go,”
says Most. “If you believe film is the
only acceptable aesthetic, or the most
desirable one, then you should try to
find a way to shoot film. Manipulating
digitally captured images in a rather
destructive way in order to make them
look ‘not digital’ is, to my mind, counterproductive.
The advantage to all of
these digital formats only really materializes
if you hand that file over to the
final colorist, and in many cases, that
just isn’t happening.”
In an effort to ingest all the various
formats, resolutions, codecs and bit
depths, many post facilities have engineered
their own solutions for their
particular hardware/software pipelines.
“Secret sauces are
not helping the
workflow situation.”
In fact, many use this “secret sauce” to
promote their services. “Secret sauces
are not helping the workflow situation,”
says Cioni. “I’ll admit that there are
things I don’t know about post, but I
have not been able to find anything in
what we do that I wouldn’t share with
someone else. I find that if you share
information with your clients, they are
more likely to come back to you.”
A discussion of workflow can
quickly get bogged down in technical
terms such as color space, color gamut,
linear, log, bit depth and so on, but these
image parameters play a crucial role in
the quality of the images they display. It
is vital to understand that different
devices and post steps “speak” in different
color-space languages, and that in
order to move an image through a
specific workflow, it is often necessary
to transform the image from one color
space to another.
In fact, transforms can occur at
almost every step in the post process.
The original camera files, for example,
must be ingested into a color-corrector
platform in order for the images to be
graded. If you’re shooting on an Alexa
in Log C to ProRes files, for instance,
you must choose what color space to
perform your color corrections in, such
as Rec 709 for HD broadcast or Blu-ray
finish, or the DCI P3 standard for
theatrical exhibition. Either way, a
transform occurs.
The process of transforming an
image can significantly impact the
results. Cioni explains, “When you
transform from one color space into
another, the result cannot be exactly the
same. The only way for it to be exactly
the same is for it to be in the same color
space. So when doing a transform, there
has to be some percentage of change. If
it’s less than 1 percent, it’s probably not
an issue, and if it’s less than 1 percent in
the highlights, that’s even less of an
issue.
“For example,” he continues, “if I
showed you a series of pictures and said
the difference between them is that one
has white at 100 percent, one has white
at 95 percent, and the final image has
white at 90 percent, you probably
wouldn’t see much of a difference. But if
I were to show you images with black at
zero, black at 5 percent and black at 10
percent, you’d probably be throwing up
by the time we got to 10. It’s the same
amount of variation, but where you put
[that variation] changes the perception
of what you see. When transforming
between color spaces, you want to make
sure that the transforms upset areas in
the image that are the least detectable.”
A loss of image quality can occur
when transforming imagery captured
by a modern digital-cinema camera,
Diagram courtesy of the Academy of Motion Picture Arts & Sciences.
80 January 2012 American Cinematographer