WPF has impressive rendering capabilities, and by using RenderTargetBitmap Class
] you can leverage that functionality to create bitmap images.
If you want to go into sub-pixel accuracy then Anti-Grain Geometry
] may be just what you need. It's a C++ library, but you can access the functionality by leveraging C++/CLI mixed mode. What you get out of anti-grain is "professional" quality imaging capabilities.
If you want to look at a complete imaging solution gimp
], the GNU Image Manipulation Program, can be used as a learning source. It's open source.
Anti-Grain and gimp goes beyond what's currently available in WPF in their respective areas - obviously you can use them as background material if you want to accomplish something similar using c# and WPF.