Spatial-frequency method of document control

Authors: Nikolaev S.A.
Published in issue: #5(22)/2018
DOI: 10.18698/2541-8009-2018-5-314
Category: Instrument Engineering, Metrology, Information-Measuring Instruments and Systems \| Chapter: Laser and opto-electronic systems
Keywords: document circulation, microscopy, spatial-frequency methods, spatial spectrum, reflected light, depth of focus, normalized light, RGB color measuring system
Published: 11.05.2018

The aim of our research is to develop a spatial-frequency method of determining the chronological sequence of plotting the hand-written and printed texts in the cases when the specified texts do not have intersection regions. The desired goal is achieved by means of metallographic examination of the samples and analyzing the spatial-frequency properties of the data received. The essence of the suggested method consists in changing the sharpness of the images obtained during the observation through the microscope under inessential defocusing with regard to the toner particle. It is shown that the integral spectrum of high spatial frequencies in the image focused inward the layer of the paste or gel in 2 or 3 times exceeds the corresponding spectrum in the image focused outward this layer.

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