Videofeedback Accelerations

When one points a videocamera back at its own monitor the phenomenon of video feedback occurs. By connecting a vision mixer in between the camera and monitor chain, and by adjusting various picture parameters such as colour balance, relative size, brightness, contrast and sharpness, the results can be extraordinary. Single camera feedback involves one videocamera feeding back an image to its monitor. In dual-camera video feedback, two cameras are pointed at the same monitor. Again a vision mixer takes the output from each camera and displays the combined image. A vision mixer is essential in dual-camera feedback, since there must be control of how much of each picture is displayed. The examples shown here incorporate dual-camera feedback with mirror image feedback of the image, producing very symmetrical results.

Like the "Doctor Who" video feedback titles created in the 1960s, the examples here are all symmetrically filmed. Not only has optical feedback been used, but also internal feedback from the vision mixer itself. If the output from a digital vision mixer is fed back into one of its video inputs, then this can be another way of creating a type of signal feedback that can be used in a creative way. This additional variety of processing can be applied to already filmed sequences to add ghostly effects, or to add temporary colour to monochrome pictures. The examples show multi-layered optical video feedback with multi-layered internal feedback superimposed on various backgrounds. Quite complex video sequences can be built up this way, adding layer upon layer creating combinations of colour and movement that can be dynamic and very interesting to anaylse.