German Artists and Artisans
The Clark Art Institute in Williamstown, Massachusetts is noted for its works by Monet, Renoir, Vermeyen, and other famous artists. The Institute also houses a remarkable research library that contains many publications of interest to family history researchers who are tracing families of artists and artisans. This library has a wide range of general biographical dictionaries of artists as well as many publications relating to the study of specific artisans.1
By searching their online digital collection you may view many portraits painted by master painters such as Lucas Cranach, Albrecht Dürer and others. You may search for German notables such as Philipp Melanchthon or Cardinal Albrecht of Brandenburg, Archbishop of Mainz and be able to view their images.
1 The Clark Art Institute's catalog is available here.