A method for inspecting a surface of a printing medium, the method comprising the steps of acquiring an image of the surface or a portion thereof, digitizing the acquired image whereby a digitized real representation of the surface or portion is obtained. The method also include the step of for each of said digitized real representation performing either or both of the steps of comparing said digitized real representation with a digital reference representation, said reference representation being a virtual digital fault-free representation of said surface or portion thereof and determining whether said real digitized representation is in compliance with stipulations of a set of rules which define the characteristics of a fault-free digital representation of said surface or portion, and providing either a correct indication output signal where there is a match between said real digitized representation with said reference digital representation in the case of the step of comparing or compliance with said rules in the case of said step of determining, or fault indication output signal where there is a mismatch in the case of the step of comparing or incompliance in the case of the case of determining.