And just to add: it is called "conflation" artifact and this is what AntiGrain Geometry used the [compound shapes](http://agg.sourceforge.net/antigrain.com/news/release_notes/v24.agdoc.html#toc0007) rasterizer for, see:

 ![flash_rasterizer.png](http://agg.sourceforge.net/antigrain.com/demo/flash_rasterizer.png)

Also, this is what NV Path Rendering claims to improve on:

[An Introduction to
NV_path_rendering](http://developer.download.nvidia.com/assets/gamedev/files/An_Introduction_to_NV_path_rendering.pdf) (p. 67) or [NV_path_rendering FAQ](http://developer.download.nvidia.com/assets/gamedev/files/NV_path_rendering_FAQ.pdf) (#29).