im_lowpoly(img, threshold, edg_amount, mid_amount)

converts an image to low-poly style

This function aims to convert an image to low-poly style.
The core algorithm is the following:
1. using edge detection to determine the boundary of the image
2. randomly choose a portion of points on the edge
3. randomly choose certain amount of points from the image
4. generate delaunay triangulation with the combination of aforementioned point sets
5. colorization the triangulation. the color is determined by the color on the center point of each triangle
Examples of processed images can be viewed at Github: https://github.com/zhohu/low-poly