COLORS ANALYSIS AND TECHNOLOGICAL ERRORS IDENTIFIED IN PRINTING OF ROMANIAN POSTAL STAMPS

Abstract

Papers of value such as banknotes, stamps, stocks etc. are typographical products which are executed using special technologies which should ensure their protection against forgery. In order to verify their security elements, a digital comparative instrument has been designed and manufactured. This contains two digital microscopes mounted in parallel which can move simultaneously on the Oz axis and an adjustable and graded support for positioning the samples on the Ox and the Oy axes. The microscopes are calibrated from an optical and spectral standpoint at the beginning of the study based on the imposed tolerances. The visual field of the microscopes is illuminated in a controlled manner according to a standard light source, to properly ensure the correctness and consistency of the measurements. In this article, the experimental devise is used to record and analyze comparatively the colors and dimensions of the Romanian postal stamps to identify the technological printing errors.