Towards collation with digital images

With hand press books, there can be variants within the same setting, as a result of corrections made while the print run is in progress. These "stop-press variants" provide important clues to reconstruct the process of book production and discover practices unique to certain printing houses. Without collation, stop-press variants are very difficult to detect because they can be rather subtle. This article reviews methods and instruments that have been used to collate printed books in the past, such as the Hinman Collator. It goes on to describe the merits and demerits of these methods, and define the necessary and desirable requirements for collation - especially for collation of early printed books in Europe. This paper proposes a new approach to precise collation that makes use of the superimposition of digital images. In addition to being less costly, this approach is more detailed, more precise, and easier to implement than previous methods. Furthermore, it provides an objective way to identify differences. Two methods of applying the principle of superimposition, static and dynamic, are given along with technical details and software requirements. A case study is also discussed.