METHOD AND DEVICE FOR SECURING DOCUMENT

摘要

PROBLEM TO BE SOLVED: To provide a method and device for securing a document.SOLUTION: A method includes a step of printing a distribution of dots 110 on a document in which an unpredictable fluctuation of at least one geometric property of the printed dots 110 occurs for each of the dots 110 as the result of unexpected unknown elements in printing; and a step of generating a distribution of the dots 110 in which the dots 110 of the distribution have at least one geometric property that fluctuates among the dots 110 and the geometric amplitude of the fluctuation which occurs has the scale of the above mentioned unpredictable fluctuation before the printing step. In the above mentioned distribution of the dots 110 in the generation step, at least half of the dots 110 in this distribution are not arranged laterally with respect to the other four dots 110 in the distribution of the dots 110, and at least one dimension of at least a part of the dots 110 of the distribution of the dots 110 is almost equal to a mean value with respect to the absolute value of the above mentioned unpredictable fluctuation.