Qing Luan Steven M. Drucker Johannes Kopf Ying-Qing Xu Michael F. Cohen Annotating gigapixel images. 33-36 2008 UIST http://doi.acm.org/10.1145/1449715.1449722 conf/uist/2008 db/conf/uist/uist2008.html#LuanDKXC08