METHOD OF PROTECTION OF MATERIAL INFORMATION CARRIED OUT BY LATENT ELEMENTS

The method of protection of latent elements for the printed documents at the stage of preprint preparation with the further withdrawal of printing forms and prints is developed. The choice of the minimum thickness of lines for the offset printing method is substantiated. The measurements of the relative size of the raster point, optical light shrinkage when printed on different papers are studied using the Sheberstov-Murray-Davis formula. The study of the properties of fifteen paper models used for printing and their densitometric indices, which influence the quality of printing, are shown. The comparison of thin lines with offset printing and office equipment, which uses the method of printing an electrophotography, is carried out. Digital protective latent elements are developed. A graphical way of protecting printed documents is created by creating hidden images when choosing high resolution lines. The method of protection is that for the protective elements, the displacement of the part of the lines of the raster is formed by half the size of the step of the raster lines. Improved latent element protection by overlaying fractal nets, which makes it possible to create graphic traps. The printing of developed protective elements on paper models has been investigated. Protective items are printed on Heidelberg offset printing machine. From the prints there are made copies which, compared with the originals, using the method of pixel comparisons of the signal-to-noise ratio, the results of comparing the originals among themselves, the originals and their copies are presented in this paper. Experimental research was conducted on the basis of the Full Pixel Comparison (PSNR) method of the original of the protective element printed on the offset machine with the original, and the original with its copy. On the basis of researches the reliability of documents is established. Also compare the originals of documents among themselves.