The paper describes an investigation into three similar methods of reducing the bandwidth required for the transmission of television pictures. The three methods all involve the isolation of the essential brightness changes in the picture; these are redistributed to occur at a uniform rate for transmission. A second signal must be transmitted in order to allow correct repositioning of the brightness changes in the final picture. Partial instrumentation has been carried out, and the methods have been assessed with regard to their bandwidth requirements and resultant picture quality.