Flexibility of the available digital images:   The digital images can be accessed by available paint programs and the richness of the detail examined and modified.  For instance the above illustrated 1280x1024 screen paint program window holds a 1:5 zoomed Plate from Strecker (1877) and a 1:1 cut from that plate which has been enhanced by removing the yellowing of the book paper.  The large digital image format is not available over the WWW but is made available to interested individuals via a CD-ROM, Catocala Moth History (Professional edition).