Re: how much of what we see is black?

From: Jonathan Walley (email suppressed)
Date: Sat Nov 03 2007 - 15:06:17 PDT

This has been a fascinating discussion - Frameworks at its best (and
Frameworkers at theirs)! But grading and lesson-planning pile up, and
duty calls. Still, I think it's worth responding to one of Flick's
points. I agree that the Kodak passage, while very interesting, seems
to contradict itself in the manner Flick describes:

> And come on, Kodak dude: 
> "The second 'positive' is the eye/brain hanging on to the image after
> the image has disappeared."
> followed by:
> "If we stored the previous image in our minds it would overlap with
> the next one and cause the effect of motion blur."
> So - is he saying there's a positive afterimage or there ISN'T a
> positive after image? "The eye/brain hanging on after the image
> disappeared" or not?

But I disagree with the following:

> And the plain logic of p.o.v. theory is - if the shutter is timed
> properly, the after-image lasts ONLY long enough for the next real
> image to arrive.  There's no overlap, or piling up.  The p.o.v. lasts
> ONLY long enough that we miss the blackness of shutter-closed.

Keep in mind, though, that different projectors produce different
flicker rates, which means different durations of blackness between the
frames. Thus, it seems unlikely that there's no POV "pile up" because
the duration of the black between frames is perfectly aligned with the
duration of our (hypothetical) POV. And I assume that the degree of POV
would depend in part on the brightness of the image, which varies
depending on the qualities of the image itself (what's in the picture -
a bright sunny day in the desert or a dimly lit street at night?) and
the intensity of the projector bulb. These variations would seem to
mitigate further against the possibility that the duration of black
between frames is timed perfectly to the persistence of an image on our

Also, and maybe I'm getting a bit too far into the speculative here, if
the reason we couldn't see the black spaces between frames was that the
light of the images remains "burned" - however briefly - on our
retinas, then couldn't we hypothetically see one of those black frames
if we kept our eyes shut and suddenly opened them? If we kept doing
this while watching a film, wouldn't the law of averages dictate that,
at least some of the time, we could "catch" a black frame by preventing
our retinas from getting "burned?" But we never do. I don't, anyway.

> If the blackness was too short, the images would overlap slightly, but
> our brains could clearly handle that, since that's how we see the real
> world.

But do we really see the world as a series of images? Perception of
reality is different from filmic perception in precisely this way, no?

Or is it? In an essay entitled "Is perception discrete or continuous?"
(in TRENDS in Cognitive Sciences Vol.7 No.5 May 2003) Rufin VanRullen
and Christof Koch put it this way:

"In the quest for the neuronal correlates of consciousness, time is an
important but often ignored variable: when percepts arise is probably
as fundamental a question as where they do. How do percepts and their
neural representations evolve over time, both when the outside world is
standing still or when it is abruptly changing, such as during an eye
movement? Do we experience the world as a continuous signal or as a
discrete sequence of events, like the snapshots of a Multimedia
Component camera? Although the subjectively seamless nature of our
experience would suggest that the relevant underlying neuronal
representations evolve continuously, this is not the only possibility.
Conscious perception might well be constant within a snapshot of
variable duration."

Long and wooly passage, I know, but thought-provoking. As has been this
whole exchange.



Jonathan Walley
Assistant Professor
Cinema Department
Denison University
Granville, Ohio 43023
email suppressed

p.s. I have the whole essay as a pdf, and would be happy to send it to
any interested parties.

For info on FrameWorks, contact Pip Chodorov at <email suppressed>.