1. A method of one-dimensional redundancy reduction coding, transmission and decoding of binary image data by use of an entropy preserving algorithm, the image data of the type including two-level pel representation of an image to be transmitted, comprising the steps of: (a) generating an image definition comprising a serial stream of binary data bits, each bit representing a single pel of either a first level or a second level; (b) assigning a predetermined binary code N having a number of data bits n representing a runlength of consecutive pels of a single level; (c) assigning a prefix P for defining with N a codeword representation of a runlength, the prefix P having a number of data bits p, whereby the total number of data bits representing each runlength of pels is defined by a codeword comprising a prefix P and a code N having (p+n) data bits; (d) concatenating consecutive codewords; (e) framing the concatenated codewords into output words W each having a fixed, predetermined number of data bits w; (f) transmitting the output words; and (g) receiving and decoding the transmitted output words for generating therefrom a serial stream of data bits, each bit representing a single pel of one of said levels, by searching in said output words for the prefix P associated with a codeword and identifying therefrom the (p+n) bits associated therewith.