Method of technical protection of printed matter from falsification
This invention covers a stage of preparation of securities for printing. The method of protection consists in inclusion in the algorithm of screening additional variables and factors between the values determining the character of a raster (the angle and periodicity of construction, and also the form and proportions of conventional dot gains), thus heterogeneity of a raster may not visually change the image transmitted or be tonally distinguished. As additional variables, there may be used random numbers, functions, and the content of additional images or the information array, capable to make distortions more complex, and also to transfer the latent information in a raster. Thus, not limiting a capability of the designer, it is possible to receive a final composition with the high enough degree of uniqueness of a pattern in a short term. If a not too fine raster grid is used, the presence of distortions and their character can be determined with the naked eye. Defining the authenticity of a sample, the experts may use a control pattern, a raster of which does not contain the image, but repeats the geometrical structure of an original raster. If the geometrical structure of the ordered raster does not coincide with a pattern, a moire arises at imposing.