'Pastels' is driven by automated features extracted from an image using a combination of SURF, KLT, PoTrace and manual
A voronoi graph is computed given these feature points, combined with the underlying pixel data from the original
image we execute the core algorithm which generates flat colour (but low-alpha) squares.
Each square is technically a polygon, each side of the square beign sub-divided slightly to provide texture, each
square also being layered a number of times with varying small pertubations to the position.
We calculate the size of squares from the voronoi graph, the small the square is, the more solid the outline.