Abstract: A generator for generating shapes derived from a square comprises a memory for storing the values of the function .vertline.X.vertline. and a memory for storing the values of the function .vertline.Y.vertline., an adder for delivering a value M=.vertline.X.vertline.+.vertline.Y.vertline., and a memory for delivering control signals to a video switcher as a function of the value of M. In the case of points located inside a square corresponding to the equation .vertline.X.vertline.+.vertline.Y.vertline.=K, the value of M is smaller than K. The address values X and Y are computed as a function of the coordinates of the point considered in the image to be generated and as a function of the geometrical transformations to be made in the figure in order to vary its shape and its position.