A T.V. picture processing system comprising an input arrangement for receiving T.V. picture information and converting it into a form suitable for an input processor. The input processor modifies the size of the picture from information received from the input arrangement. A store is provided for storing the input processed picture information. A co-efficient generator is connected to the store for providing modification of incoming data to the store in dependence on the co-efficient generated and on data previously stored in the store. An output processor is provided for modifying the size of the picture from information received from the store and an output arrangement receives the information from the output processor and converts this into a composite T.V. signal.