Abstract: A method and apparatus for checking deviations in dimensions and contrast of patterns 1 which are presented for checking purposes at a practically constant speed v of a continuously variably adjustable magnitude, in particular of identical patterns 1 printed on a repetitive fixed area 3 on a strip 2 of flat carrier material 30, each pattern 1 consisting of parallel lines of bar codes printed at predetermined mutual distances, by optically forming an image of each pattern to be checked upon a fixed format and by taking several traverse images therefrom at an angle .beta. with respect to the direction 6 of the bars by means of the row(s) of closely arranged electrical sensing elements, said traverse images being read out serially and subsequently entered into an electronic arithmetic apparatus for comparison with a reference pattern.