Abstract: A one-dimension transformer for use in Transform Picture Coding converts each of a series of N input words into a series of N product words by multiplying this series and a transform matrix of N.times.N transform elements. This transformer has a main input connection bus (14.22) which receives the series of input words, a main output connection bus (14.29) at which the desired N product words occur successively and furthermore three data connection buses (14.23; 14.24; 14.25). For performing the required mathematical operations three circuits are provided; two combination circuits (14.30 and 14.31) for adding or subtracting data words applied thereto to generate result words at their outputs and a multiplier circuit 14.32 for multiplying a data word applied thereto by a mulitplication factor which is related to the transform elements to generate an auxiliary product word at its output. The associated output of each of these three circuits is connected to a different one of the three data connection buses.