Can someone explain to me why does this happen?

Hi guys, I pointed my webcome to it's feedback from the monitor, this
is what I got.

http://video.google.com/videoplay?docid=6522668723433215632&hl=en

It is weird, I understand the visual vortex that forms when the camera
picks up the image that it captured just previously but where do the
colors come from?

Fede

 

Flaws in the camera. I did a lot of playing around with feedback
and other analog distortions back in the mid 70s (we built an exhibit
for Boston's Museum of Science). One of the things we learned
was that a crummy camera made much more interesting feedback
than a broadcast camera.

David

 

Hi David, do you have anything that I can see online? I guess if it was
back in the 70s but have you digitized comething?

 

Remember that single-chip color cameras (such as your
"webcam") form colors by dividing up the light-sensitive
chip surface between the different primary colors (or some
equivalent). A slight shift in position will slightly change the
color which will be quickly multiplied into saturation by the
video feedback into one of the primary (red, green, blue)
or secondary (magenta, cyan, yellow) colors. Note that
those six colors (along with hard black and white) are the
colors you recorded (and not coincidentally, also the colors
in the SMPTE color bar test pattern).

 

Sorry no. Almost none of it made it to tape, and I don't know if I even
still have any of it.

It was mostly just experimentation to decide how we wanted to build the
exhibit.
The exhibit was called "Vision and Television". The first half attempted to
explain
how vision works in humans and various other animals, and the rest was what
they called a video synthesizer. It was a round room with mirrored walls and
a
lot of video monitors (modified TVs). Some of the TVs could have their scans
distorted by feeding signals into coils around the neck of the CRTs, there
was
also adjustable quantization, and other effects. The part you would have
liked
was the camera mounted in the center of the room on a motorized pan and
tilt,
plus another rotator that moved the camera on the X axis You could point the
camera at monitors and mix it with other effects to create some weird stuff.
This was before the microprocessor was common, so just about everything
was totally analog. There were some logic chips involved but that was it for
digital.

David

 

Very Cool Thanks for sharing, it sounds like quite a complicated settup
you got back then, now you can do it with a $30 cam and a computer.

Fede

 

One of the tricks was that it had to be usable by several visitors at the
same time and be interactive. Plus it had to hold up to inner-city kids.
They tell a story about a guy that built a modified bicycle that was
hooked up to a generator that would light a light bulb when you
pedaled the bike. He built it at home and had all of the neighborhood
kids over to test it. As far as he could tell it was robust enough for
kids to play with without breaking it. So, he delivered it and set it
up, watched the children playing with it, then went up stairs to
collect his final payment. On his way out he dropped by his exhibit
to see how it was doing, and the kids had disassembled it and
stolen some parts. He was in tears.

David