Areal coverage of primary colours in measuring segments of multi-coloured offset print originals independently of the spectral reflectance characteristic of the inks concerned, eg in the case of four-colour printing, merely the degree of areal coverage of the three colouring inks in a measuring segment, is determined by photo-electronic measurement of reflectances and solution of the Neugebauer equation system, whilst the areal coverage of the colour black is determined by image analysis after additional scanning of three digitalised image extract images from the same measuring segment. The apparatus comprises a first beam splitter (5) for division of the light beam from the objective (4) and transmission of part thereof to measuring head (9), a second beam splitter (6) having three light exit surfaces (7) provided with red green and blue filters having associated colour-selective sensors to produce colour extract images for connection to image analysis means 8. <IMAGE>
VERFAHREN UND ANORDNUNG ZUR BESTIMMUNG DER FLAECHENBEDECKUNG DER PRIMAERFARBEN IN MESSSEGMENTEN MEHRFARBIGER DRUCKVORLAGEN EINER OFFSETDRUCKMASCHINE