There is no checkbox labeled with "Anti-aliasing" in the tab "Image". I checked the settings in the following way (in the German version):
File / Export / Save as HTML ImageMap (*.html) / tab "Image"
There are only 4 fields (in German):
* Auswahlmarkierungen zeichnen (checkbox)
* Grafikformat (=JPEG)
* Kantenglättung (checkbox)
* Bildqualität (0,1 - 1,0) --> current setting = 0,8