1. A method for selecting a characterizing algorithm for generating a first characterizing information descriptor for a block of printed material on an object, wherein, at a location distant from where said block of printed material is printed, said block of printed material is to be scanned from an object, the block of printed material is to be used to generate a second characterizing information descriptor, the first characterizing information descriptor is to be retrieved from an indicium on the object, the retrieved first characterizing information descriptor and the second characterizing information descriptor are to be compared, the indicium is to be determined to be valid when the retrieved first characterizing information descriptor and the second characterizing information descriptor match to a particular extent, and the indicium is to be determined to be invalid when the retrieved first characterizing information descriptor and the second characterizing information descriptor do not match to the particular extent, said method comprising the steps of: a) printing said block of printed material on the object; b) applying each characterizing algorithm from a predetermined set of characterizing algorithms to a pristine image of said block of printed material to generate a plurality of corresponding first characterizing information descriptors for said block of printed material; c) determining, by a computer system, estimates of robustness, with respect to said block of printed material, for each of said characterizing algorithms in said predetermined set to determine which of said characterizing algorithms has the highest estimate of robustness, wherein robustness is a measure of the extent to which a respective characterizing algorithm produces characterizing information descriptors that result in the same above determination of validity or invalidity of indicia for the pristine image of the block of printed material and the scanned image of the block of printed material after the block of printed material has been printed on the object, despite differences between the pristine image of the block of printed material and the scanned image of the block of printed material after the block of printed material has been printed on the object; d) selecting the characterizing algorithm with the highest estimate of robustness; and e) printing the indicium on the object, the indicium storing the first characterizing information descriptor generated by the characterizing algorithm with the highest estimate of robustness; wherein the block of printed material is text; and wherein all characterizing information descriptors are information, describing the block of printed material, which may be stored in the indicium but are not merely the indicium itself.