The book "High-Quality Horn Loudspeaker Systems" contains a vast number of photos, diagrams and graphs. In fact the authors have not kept track of the number of illustrations, could be a couple thousand. We decided to make the book in a large page format with two text columns. Illustrations are therefore mostly either one or two columns wide. Even the authors might object to how some of the 1-column wide illustrations come out on the small side and are actually a bit difficult to read. Some response graphs reproduced from old sources, for instance, have typewritten text which comes out very small in print. The printing people specified that all graphics had to be formatted for at least 300 dpi resolution to come out good in print. This means that even the smaller illustrations can come out in quite good resolution. We can therefore only recommend good lighting and a good magnifying glass or loupe to accompany the reader.
1920s-1930s photographs originating from the Bell Telephone Laboratories History Museum archive were photographed with medium format cameras. The filed prints we could scan were often amazingly detailed and were scanned by the authors in 600dpi resolution. The full resolution of these photos can not be reproduced in the book, and invariably these photos are reproduced in a smaller format in the book. Because of the very large number of illustrations we wanted to include in the book, we had to conserve space and apologize for how some of them have therefore come out "too small".