New, Camera-Based Quality Measuring Methods for Newspaper Printing

The research of the on-line quality measuring of newspaper printing reported at TAGA `91 has been continued. CCD camera-based, microscopic measuring of the screen dot area and systematics to relate changes in the dot structure and quality to the variations in the ink/water balance are developed. New methods are studied to define the colour register errors directly from the printed image and an off-line measuring system is developed. The accuracy of the developed method is more than | 0.1 mm with a suitable measuring point. A prototype project for utilizing pre-press data in the automatic colour quality inspection of the printed web is reviewed briefly.