Measuring and correcting print-to-print register of a multicolour print formed on printed material

A process of measuring a print-to-print register of a multicolour print provided in an effective printed area of a surface of a printed material, the multicolour print being formed on the printed material by way of a printing press and including at least a first pattern and a second pattern distinguishable from the first pattern, the process comprising:

• forming the multicolour print on the printed material in several consecutive passes by way of multiple printing presses, the printed material being provided with a combination of printed patterns produced in accordance with different printing processes so that the multicolour print results from a combination of an offset-printed pattern and an intaglio-printed pattern;
• providing a matrix arrangement of individual imprints with the multicolour print in the effective printed area, each imprint being repeated over the surface of the effective printed area along a pattern of rows and columns;
• deriving a set of multiple measurements of an actual print-to-print register between the first and second patterns at various imprint locations over the effective printed area by repeating for multiple ones of the individual imprints processing and finding a correspondence between:
• (i) at least one sample image of the printed material covering at least a portion of the first and second patterns;
• and
• (ii) at least one corresponding reference image generated using prepress design data of the first and second patterns;
• mapping the set of multiple measurements into a corresponding print-to-print register map that is representative of print-to-print register deviations at the various imprint locations,
• wherein said correspondence between the at least one sample image and the at least one reference image is found by performing a cross-correlation between the at least one sample image and the at least one reference image, the cross-correlation including finding an optimum of a correlation function between the at least one sample image and the at least one reference image.