Introduction to Feedback

Introduction to Feedback

Those of you who own a video camera may have tried pointing it at the TV screen. The effect you see is the result of feedback. The video camera recieves an image which, after a small delay, is displayed on the TV. The camera sees what it on the screen, and sends that image back to the TV. The image continues looping round the system.
However, the camera does not see perfectly, and the TV does not display perfectly. These imperfections are multiplied as the image is constantly passed between TV and camera. What it left is some interesting pattern. Any slight changes in camera position, roll, zoom and focus will cause a change in the pattern produced.

This cycle can be reproduced on a computer. Computers, the flexable beings that they are, can do many more effects. They are not limited to rotating, zooming etc, but can also manage bending, squashing, warping etc.

Time for a picture:

Start with an image. Apply some kind of modification to it. Display the image. Continue this cycle. The modifications will build up and the image will become more and more distorted.

You can combine modifications, leave it up to your imagination.
As the cycle continues, numerical errors will build up, and you will loose image quality. To combat this, you can try adding some constructive effects to the cycle as well as the modifications. For example, you can mixing in the origional image evert frame.

A small example

1.

Origional Image.

2.

After rotation and scaling down.

3.

Mix with origional image.

4.

Rotate and mix again.

5.

Rotate and mix again.

6.

Rotate and mix again.

That was a very simple example. Every frame, exactly the same modification was applied. More interesting effects can be achieved by using a slightly different modifier each frame. For example you might alter the amount the image is rotated each frame.