Synfig Studio
Synfig Studio is a free, Open Source 2D vector and timeline-based animation application. You 
can use Synfig Studio to create feature-film-quality animation, web animations and 
advertisements.
Key Features Include:
Spatial resolution-independence:
Most elements are vector-based and all layers are parametrically generated, hence even when 
changing the target resolution of a project, the only pixelation will occur in imported raster 
images, not the built-in components.
Temporal resolution independence: 
Animation-keyframes are automatically interpolated by the computer, resulting in smooth 
motion.
High Dynamic-Range Imaging:
By using floating-point math in the image calculations, HDRI processing allows canvases to 
internally understand a far greater range of pixel luminance, resulting in better lighting 
effects, and improved color composition.
Pentablet-friendly tools:
The draw tool already reads the pressure sensitivity channel off your favourite tablets, for 
natural line weighting, and more to come!
Artist-oriented design:
Synfig has been designed from the ground up with animation workflow in mind.
Path-based Gradients: Synfig has full support for gradient paths - gradients 
that follow along a drawn shape. This allows artists to easily add soft shading to animation 
without the trouble of painting it onto every frame.
Layers: Synfig supports a multitude of layers of various types; geometric, 
gradients, filters, distortions, transformations, fractal and a few others.
 Synfig Studio is a feature rich application that has numerous features 
including High Dynamic-Range Imaging (HDRI) and artist-oriented design and path-based 
gradients.