Digital Dream Studio
DDS is a image generating and editing software, which is currently freeware. What sets it appart from other similar programs is the ability to fine-tune even the low-level options of each one of its tools. Brush shapes, blending modes, fadings, layer proprieties, flood fills and spline curves - all of them and many more can be defined in great detail, by the user. Furthermore, the features offered by DDS can be easily extended by adding new plug-ins (the communication protocol between the host and the plug-in is simple enough for even the beginner programmer to use).