Abstract: To permit panning and tilting of the foreground camera when composite images are being produced by the color separation overlay or chroma-key technique, signals representing the panning and tilting motions of the foreground camera are used to control the movement of the background image in front of the background camera in two mutually perpendicular directions.

Abstract: In apparatus for generating a signal suitable for application to a television receiver, signals corresponding to highlights in the output of a television camera are detected and removed or replaced by signals having a value less than a threshold value, the signal thus modified being used to control an iris or equivalent means for controlling the response of the television camera to a given light input.

Abstract: When a load is to be moved between preselected points along a path such that its weight aids movement in one direction and opposes it in the other (for example when scenery supported from a hoist is to be moved between "deads" in a theater or studio), the supported load is initially weighed and a signal representing its weight is stored. This signal is extracted from store when movement between positions is required and is applied to the hoist driving system to provide a torque balancing the load weight before a brake on the hoist driving system is removed. Thereafter the load is moved to the new position, the brake is reapplied and the stored weight signal is removed from the driving system.