1. A method for antiforgery marking of lots of printed products (P) that are to be printed with a given single original printer (S), comprising the following steps: printing with said single original printer one or more physical guide prints of a master digital image that form part of a lot of printed products; digitally acquiring said one or more guide prints to obtain one or more synthesis digital images; processing said one or more synthesis images to extract therefrom one or more intrinsic characteristics uniquely identifying the single original printer; creating at least one identifier code (CI) by encoding information associated to the product and information associated to the characteristics uniquely identifying the single original printer; creating an identification marking (M) of the product (P) comprising said identifier code in combination with said one or more guide prints already present on the product; and applying said marking (M) to the products (P) of said lot, wherein said processing of the synthesis image comprises a numerical characterization of the synthesis image capable of obtaining a digital signature uniquely identifying the single original printer, said numerical characterization being performed using one or more image-processing techniques selected from among transformed-domain processing techniques, statistical-approach techniques, techniques based upon shape and texture descriptors, techniques based upon multi-channel analysis of the acquisition channels, or combinations thereof.