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Video Feedback Overview
Video feedback is the process of pointing a camera at the screen displaying the camera's output. This creates a feedback loop of images infinitely repeating onto and over themselves creating interesting patterns. An initial curious result has become a studied phenomena that relates to other sciences such as cellular automata, reaction diffusion and non-linear dynamics.
This page has information about real and simulated video feedback.

Video Feedback Setup
All you need is a camera and a monitor or TV capable of displaying the camera's output.
Any camera and monitor/TV combination will usually work. Different quality cameras and screens will all lead to unique results.
Video Feedback Setup
An example setup from James Crutchfield's paper.

Video Feedback Tips
If you want to experiment with video feedback, here are a few tips for getting interesting video feedback results;
1. Try experimenting in a darkened room. Excess light tends to cause "white outs".
2. Play with all the controls the camera and screen have (brightness, contrast, invert, solarise, zoom etc).
3. Make changes to brightness etc slowly as large changes can quickly lose a nice setup.
4. Try rotating the camera 180 degrees (upside down) in relation to the screen.
5. Set the zoom so it is close to the sweet spot of not zooming in or out too quickly. That way patterns tend to slowly grow and shrink.
6. If you have a video mixer with effects put that in the loop between the camera and screen or screen and camera.
7. A tripod will help keep the camera steady when a good pattern is found and allow small adjustments to angle.
8. Make sure you have some way of recording to capture interesting results.
9. If you lose a nice feedback setup to the screen going black a quick flick on/off the lights to seed the screen can get it going again.

Examples of real video feedback
Firstly, James Cruitchfield's results from back in 1984 ...
... and some other examples I found on YouTube.

Video Feedback related links
Joel Cadman - Spinning Lights
Jose Maria Castelo - Video Feedback Explorations
Anja Franz - Oil paintings of video feedback
Chaim Goodman-Strauss - Fractal Feedback
Tom Holroyd - Dr Tom's Video Feedback Gallery
Peter Henry King - Video Feedback Fractal Genesis
Lari Lucien - Images of video feedback and video feedback using analog image mixers
Paul Prudence - Talysis.
Wikipedia - Optical feedback

Simulating video feedback
The following movie is a sample of some results from attempting to simulate video feedback.
Created with Visions Of Chaos. See SimulatingVideoFeedback.pdf for more details.

More video feedback simulation
Years after the above simulation attempts I was inspired again to try new methods of simulation.
The following movie is a full HD 1080p ten minute example of what the new simulation produces. This really needs to be watched full screen at the full HD resolution.
Created with Visions Of Chaos. See this blog post for more details.

Even more video feedback simulation
Created with Visions Of Chaos. See this blog post for more details.

Other attempts at simulating video feedback
Dimitre Lima - Feedback Synthesizer
Jose Maria Castelo - Morphogen
Alex - Web based video feedback results
Gene Shuman - Epimorphism. More here, here and here.

Scientific papers relating to video feedback
In depth and mathematical, but will be of interest to people who want a much more detailed description of video feedback.
Space-Time Dynamics in Video Feedback 1984, James P. Crutchfield
Spatio-Temporal Complexity in Nonlinear Image Processing 1988, James P. Crutchfield
Spatiotemporal Chaos 1994, M. C. Cross, P. C. Hohenberg
Pattern formation in nonequilibrium physics 1999, J. P. Gollub, J. S. Langer
Nonlinear Dynamics of Video Feedback Timothy Burt and Michael G. Lagoudakis
Farey sequences of spatiotemporal patterns in video feedback 2000, Essevaz-Roulet, P. Petitjeans, M. Rosen, and J. E. Wesfreid

Did I miss anything?
If you know of any other websites or papers related to video feedback contact me