Re: how much of what we see is black?

From: Nicky Hamlyn (email suppressed)
Date: Wed Oct 31 2007 - 07:47:40 PDT

This is surely right. If the retina is exposed to strong light, the
rhodopsin in the rods and cones becomes bleached, and the rods and
cones are thereby desensitised. The stronger the light, the longer
the rods and cones take to re-pigment/recover. Experiments have been
done in which an image has been burnt onto the retina of an animal
by this process.

  This probably helps to explain why we don't see the black moments
between frames, because they are interspersed with much brighter
ones. If the black were on the screen for longer our eyes would re-
sensitize themselves until they could see the black which after all,
is not completely black: there's always an amount of light coming
through the celluloid.

Nicky Hamlyn.

On 31 Oct 2007, at 12:39, Jonathan Walley wrote:

> I haven't re-read the essay recently, but I think the "debunking"
> is of the belief that persistence of vision is what produces the
> illusion of movement in film, and/or the illusion of continuous
> light. Do the authors actually say persistence of vision doesn't
> exist? Nobody is saying that we don't see afterimages, only that
> these afterimages cannot account for what we see when we watch a
> film. Flicker fusion, that is, isn't caused by the image of "Frame
> 1" remaining on our retinas long enough to be superimposed with
> "Frame 2," but by something else. I know "something else" is vague,
> but my understanding is that it has more to do with the brain's
> interpretations of light impulses than with the physiology of the
> retina. Cognitive rather than physiological, I guess.

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