Abstract: A one-dimensional coding method for compressing the amount of image data in facsimile machies and image filing systems. Unlike the prior art one-dimensional coding method which attaches an end-of-line code to every line, the method according to the invention attaches an end-of-line code to a plurality of lines equal to a predetermined number of lines. Alternatively, the novel method allows an end-of-line code to be attached to only selected lines according to a decision table in which are established beforehand the line numbers of the lines to which an end-of-line code is to be attached each.