Paper roughness measurement as identification and differentiation method when dealing with apparently identical graphic art printed in several copies.
The research was carried out within the framework of the European project FingArtPrint in collaboration with the ICN, Amsterdam, Holland.
The use of a confocal profilometer with white light mounted on a mechanical arm allowed us to measure the roughness ond the topography of three pairs of documents.
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Measurement of paper roughness
We measured the roughness of three apparently identical pairs of graphic documents: two etchings, two lithographs and two self-adhesive postage stamps. The image above shows the two lithographs selected for the research. In this case the roughness was measured on an area of 2x2 mm, in the middke of the right eye of the represented person.
The results of the studied cases showed that the imprint noted is unique on each work. The imprint, recorded as a three-dimensional digital topography, makes it possible to identify and distinguish each document in a univocal way thanks to the arrangement of the fibrous cushion and to the aspect of the irregularities specific to each fragment of paper.