1. A method for compressing data of two-value picture image, comprising the steps of: (a) storing an original picture image as electric signals in a memory partitioned into a plurality of regions bounded by sets of division lines for receiving divisional picture images, said sets being perpendicular to one another and each set comprising a plurality of lines; (b) detecting stored electric signals designating intersections between the division lines and outlines of a character area of each divisional picture image, individual ones of said electric signals being found as start and end points of segments of the character outlines; (c) comparing electric signals designating coordinate values of one part of a character outline with signals designating coordinate values of the locations of changes in slope, such locations being characteristic points; tracing the outlines of the character area of each divisional picture image from the start points to the end points; and (d) imaging the outlines of the character areas of the adjacent divisional picture images at the start and the end points.