Calculate the number of zoom levels using maximum rather than minimum dimension.
Calculate the number of zoom levels using maximum rather than minimum dimension.

htem/CATMAID,fzadow/CATMAID,fzadow/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID,htem/CATMAID