THE REPRODUCTION OF SMALL DETAILS ON VARI OUS GRAPHIC PAPERS IN OFFSET PRINTING

During the transmission in a printing process, dots, lines or other pl ane elements change their geometric and densitometric dimensions so th at the printed image corresponds more or less perfectly to the origina l. By means of image analysis and of the two-dimensional Fourier trans form it is possible to use line screens-as control elements - for the determination of typographically relevant values. It is thus for examp le possible to calculate the transmission loss which is inherent to pr inting form manufacturing and printing from the frequency spectrums of the line screens of original and printed matter. The transfer factor also constitutes the basis for calculating the cut-off frequency which indicates the number of safely transmitted lines per line unit and pe rmits conclusions concerning the resolving power of small details. 54 woodfree and wood-containing printing papers (coated and uncoated) hav e been tested and evaluated in respect to the reproduction of bar code s whose frequency has been varied between 10 lines/cm and 170 lines/cm . The reproduction of these bar codes is correlated with optical and s tructural parameters of the unprinted and printed papers.