A MARK-DETECTING METHOD AND APPARATUS THEREFOR

摘要

Method for detecting mechanically marks (3) or the like present on a paper web (1), comprising successively producing and preferably recording light-intensity data in the form of intensity indications. The method is mainly characterised in that when deciding whether a certain light-intensity indication (V(new)j) shall be attributed to a mark there is used as a set-point value (V(old)j) either the nearest preceding indication (V(old)j) which has been adjudged as indicative of a non-mark and which in the main indicates light background of the paper web (1), or a preceding indication (V(old)j) which has been adjudged as indicative of a non-mark and which has been subjected to an intensity reduction of predetermined magnitude (UP). The invention also relates to an apparatus for carrying out the method.