AmericanCinematographer201201

does the transform accurately from its
camera’s output into ACES RGB
values. That doesn’t have to entail going
all the way back to the spectral response
characteristics of the sensor, however; it
may be just a look-up table, if that’s the
way the manufacturer prefers to do it.”
Once in the ACES color space,
the full range of data captured from the
digital camera can then be adjusted
within a much larger bit-depth format,
which utilizes the OpenEXR container
originally developed by Industrial Light
& Magic for use in the visual-effects
arena.
“The image characteristic of a
digital camera and its sensor is unique
to each camera,” says Encore senior
colorist Pankaj Bajpai, who graded last
year’s IIF test-bed TV series, Justified.
“Each camera responds to the highlights
and shadows a little differently.
It’s analogous to how different film
stocks behave. Cinematographers can
test each camera the way they would a
film stock to learn how the blacks feel,
how the mid-tones register and so
forth, and then light the way they
always have, by eye or with a meter —
whatever method they’re comfortable
with. With ACES, when I have a scene
with a wide dynamic range, I don’t have
to chase certain areas with a power
window to bring the highlights down
the way I often had to before ACES.”
IDTs account for only one aspect
of the IIF-ACES workflow. Within
the IIF there are also transforms
for rendering (called the Reference
Rendering Transform, or RRT), transforms
specific to color-grading changes
applied to a rendered image in the
color corrector (Look Modification
Transforms, or LMTs), and transforms
that take into account the display device
used to view the output image (Output
Device Transforms, or ODTs). Clark
explains, “To make an analogy, if ACES
is your ‘negative,’ then the RRT, along
with color-grading LMTs, is your
‘print,’ the rendered negative that you
can view. You cannot make use of
ACES files independently of the RRT.
That’s also true of ODTs, which map