  Equipping the rototranslation group $SE(2)$ with a sub-Riemannian structure
inspired by the visual cortex V1, we propose algorithms for image inpainting
and enhancement based on hypoelliptic diffusion. We innovate on previous
implementations of the methods by Citti, Sarti and Boscain et al., by proposing
an alternative that prevents fading and capable of producing sharper results in
a procedure that we call WaxOn-WaxOff. We also exploit the sub-Riemannian
structure to define a completely new unsharp using $SE(2)$, analogous of the
classical unsharp filter for 2D image processing, with applications to image
enhancement. We demonstrate our method on blood vessels enhancement in retinal
scans.

Computer Vision and Pattern Recognition