Natron
Image transform (position, rotation, scale, skew).
Video tracking functionalities.
Keying: Keyer, Chroma Keyer, Difference Keyer, Hue Keyer, PIK Keyer.
Paint: Solid, Pencil, Eraser, Clone, Reveal, Blur, Smear, Dodge, Burn.
Manual rotoscoping, using Bézier curves.
A wide range of additional effects (color transforms, geometric transforms, image generators...) are available.
Key frame-based parameter animation, using Bernstein polynomials (the polynomial basis behind Bézier curves) for interpolation.
Animation curves editing : Curve Editor.
Keyframes editing : Dope Sheet.
Support for stereoscopic 3D and multi-view processing.