1. A circuit for generating object images in a video picture, said picture being formed by a multiplicity of pixels arranged as a raster scanned in a multiplicity of successive lines, in which the image of each object is presented as a plurality of segments on adjoining lines, comprising: a topological memory having memory locations corresponding to respective pixels, for storing data groups in respective locations, for each group whose corresponding pixels include a pixel which should be the start of a segment of an object image, said each data group including an identification number for a respective, specific object and the location of the pixel at which the segment starts, an object memory for storing data streams, each data stream defining a segment of a specific object, an address register for storing, with respect to an identified object, the address at which a predetermined segment is stored in the object memory, and the position in the picture where this segment is to be displayed, and means for (a) addressing and reading the topological memory in synchronism with scanning of the raster, (b) reading from the address register the address in the object memory at which data is stored defining the segment to be displayed, each time an object number is read from the topological memory, and (c) reading from the object memory, at the address read from the address register, data defining the said segment to be displayed, whereby movement of a location of an image in the picture requires a change of the data stored in the topological register only.