Superimposition - Overview

Objectives

In the course of a thorough examination of various 16th and 17th century editions of musical partitions, it turned out that copies of the same edition can contain differences, in the form of either handwritten annotations or scratched corrections carried out directly on the plate. The presence of such differences between copies is not particularly systematic. Consequently, it is not possible clearly to establish the existence of different print-runs or determine that one copy is of better quality than another. It is therefore necessary to compare all the various copies of an edition in order to make a critical edition of the highest quality.

Carried out visually, i.e. by perusing each copy note by note, the comparison of the specimens is a long, thankless task and one of often doubtful reliability. However, the few known examples of differences tend to suggest that superimposing the copies would be of invaluable help in comparing them. The aim of Aruspix is to perform this superimposition automatically, and to highlight the differences by using colours for the elements which belong to one or other of the copies to make them visually more easily identifiable, without the system necessarily having to evaluate the relevance or the meaning of the differences.

Advantages of Aruspix

Knowing that the comparison of several copies can easily take several working weeks to a person who does it conscientiously, Aruspix enables a considerable length of time to be saved. Tests carried out on several copies show that the work can be carried out ten times more quickly and in less tiring conditions.

Aruspix also improves on the results of manual comparisons. Many differences identified manually are in actual fact errors made due to the way the eye works. For example, notes corrected during the printing process were generally shifted up or down by a whole line and not by a note, or a badly placed slur was often inserted in an area which greatly resembles the correct position. Since the human eye has not changed over the last four centuries, it is probable that the person making the comparison of the copies will make the same error as the editor of the time. For this reason, a simple colour highlighting of the differences makes it possible to increase the precision of comparisons.

Future prospects

Aruspix has great possibilities. On the one hand, it makes it possible systematically to carry out the comparisons between all the various copies of a same edition, work which has never yet been carried out. In addition, it will certainly make it possible to highlight types of differences not yet identified. A person making a visual note-by-note comparison will always have certain types of differences in mind based on those already found and will be subconsciously looking only for those. It may be hoped that on the basis of new types of differences which may be brought to light, new ideas will emerge.

Aruspix also offers new long-term prospects. Perhaps it will allow the highlighting of similarities and differences not only between copies of a same edition but also between different editions, on a larger scale, by taking into account geographical criteria or criteria concerning for example the editors, owners or patrons of the editions.