As was mentioned earlier in 60137, there is no anti-aliasing in raster image export. Such functionality is rather unusable!
Win 7 64-bit Version: 188.8.131.52.alpha1+
Build ID: 56019dcb79475606952a954fe732a3109441ffec
TinderBox: Win-x86@39, Branch:master, Time: 2014-10-30_07:27:11