Abstract: It is known in the transmission of facsimile pictures to transmit the black-white data represented by one binary position per picture element via a run length coding. For the transmission of pictures in which the individual picture elements are represented by binary words having a plurality of binary positions, the individual binary positions of all the binary words are now always subjected picture line-sequentially to a run length coding and are transmitted. When a hierarchic code is used for the representation of P.E. values a compatability with the conventional facsimile receivers is simultaneously provided, which then processes only the most significant binary positions. In addition, measures for the preprocessing of the scanning values are described, so as to obtain a smoothed sequence which can more effectively be transmitted by means of run length coding.

Abstract: A first pseudo-halftone picture is converted to a second pseudo-halftone picture of reduced resolution in the ration m:n by dividing the first picture into contiguous picture fields each having i.multidot.n lines and j.multidot.n columns of picture elements in contiguous square subfields each having n.sup.2 picture elements. m.sup.2 elements are selected from each subfield in accordance with a selection sequence which depends on the position of the subfield in the picture field, the elements being selected from all i.multidot.n lines and all j.multidot.n columns of each picture field, the selection sequence being the same for each picture field.

Abstract: In facsimile transmission by means of a redundancy reducing coding, for example run-length coding, a distance affects the entire remaining portion of the picture line. End-of-line control characters are therefore transmitted for line synchronization. As these characters are possibly also disturbed and the picture lines to be printed would then completely be lost, a fixed number of different end-of-line control characters are used in cyclic sequence from line to line. This enables the recognition of various successive disturbed picture lines, lost end-of-line control characters as well as end-of-line control characters artificially produced by a disturbance, so that the correct number of picture lines is always printed. Corrected picture lines are printed instead of the picture lines which were received in a disturbed manner, for example by taking over the contents of adjacent picture lines.