1. In an image analysis system for scanning a feature with an energy beam and providing a current binary video signal having leading and trailing edges corresponding to the leading and trailing edge intercepts of said beam with said feature, and for comparing a given line scan binary video signal, stored for one line scan after the given line scan, with the current binary video signal of the line scan following the given line scan to produce a modified binary video signal having a leading edge corresponding to that of said current binary video signal and a trailing edge corresponding to the last-to-occur of the trailing edges of said current and of said stored video signal, a device for reducing the paralysis angle of the scanned feature to essentially zero, comprising: means for generating for successive current line scans and successively temporarily storing data corresponding to the X-coordinates of the intercepts of said beam with said feature for each successive current line scan; means for successively reading those X-coordinates which are currently so temporarily stored and successively selecting, as a function of data derived from successive given and current scan lines, of those X-coordinates so read, for successively storing, data defining the leading edge and trailing edge of said feature; and means for generating successive said video signals stored for one line scan having values representing the leading and trailing edges corresponding in time to those of the successively selected X-coordinates.