Film and Dynamic Range

Film and Dynamic Range
The previous section showed how color benefi ts from
precision and fl exibility. The precision is derived with the
steps just discussed; fl exibility is the result of having a wide
dynamic range, because there is a far wider range of color
and light levels in the physical world than can be represented
on your 8-bit-per-channel display.
However, there is more to color fl exibility than toggling
16 bpc in order to avoid banding, or even color management,
and there is an analog image medium that is capable
of going far beyond 16 bpc color, and even a fi le format
capable of representing it.
Film and Cineon
To paraphrase Mark Twain, reports of fi lm’s demise have
been exaggerated; not only that, but new formats make use
of tried and true fi lmic standards. Here’s a look at the fi lm
process and the digital fi les on which it relies.
After fi lm has been shot, the negative is developed, and
shots destined for digital effects work are scanned frame
by frame. During this, the Telecine process, some initial
color decisions are made before the frames are output as a
numbered sequence of Cineon fi les, named after Kodak’s
now-defunct fi lm compositing system. Both Cineon fi les
and the related format, DPX, store pixels uncompressed at
10 bits per channel. Scanners are usually capable of scanning
4 K plates, and these have become more popular for
visual effects usage, although many still elect to scan at half
resolution, creating 2 K frames around 2048 by 1536 pixels
and weighing in at almost 13 MB.
Working with Cineon Files
Because the process of shooting and scanning fi lm is
pretty expensive, almost all Cineon fi les ever created are
the property of some Hollywood studio and unavailable
to the general public. The best known free Cineon fi le is
Kodak’s original test image, affectionately referred to as
Marcie (Figure 11.9) and available from Kodak’s Web site
(www.kodak.com/US/en/motion/-support/dlad/) or the

book’s disc. To get a feel for working with fi lm, drop the
fi le called dlad_2048X1556.cin into After Effects, which
imports Cineon fi les just fi ne.
The fi rst thing you’ll notice about Marcie is that she looks
funny, and not just because this photo dates back to the
’80s. Cineon fi les are encoded in something called log
color space. To make Marcie look more natural, open the
Interpret Footage dialog, select the Color Management
tab, click Cineon Settings and choose the Over Range
preset (instead of the default Full Range). Ah, that looks
better; the log image is now converted to the monitor’s
color space.
It would seem natural to convert Cineon fi les to the monitor’s
color space, work normally, and then convert the end
result back to log, but to do so would be to throw away
valuable data. Try this: Apply the Cineon Converter effect
and switch the Conversion Type from Linear to Log. This
is a preview of how the fi le would be written on output
back to a Cineon log fi le. Upon further examination of
this conversion, you see a problem: in an 8 bpc (or even
16 bpc) project, the bright details in Marcie’s hair don’t
survive the trip.

What’s going on with this mystical Cineon fi le and its log
color space that makes it so hard to deal with? And more
importantly, why? Well, it turns out that the engineers at
Kodak know a thing or two about fi lm and have made no
decisions lightly. But to properly answer the question, it’s
necessary to discuss some basic principles of photography
and light.