1. A method for using color indicia in transmitting machine-readable information, comprising: characterizing at least one of a printing device or a sensing device for identifying a number of recognizably spaced printer output colors; using these recognizably spaced printer output colors to derive a code book, which describes how the information is to be encoded and decoded; and, using the code book for encoding and decoding the information to be transmitted; wherein the recognizably spaced printer output colors are identified as centers of clusters of associated printer output colors.