Construct convex hull from image

convex_hull_from_image.py

#!/usr/bin/env python3
from PIL import Image
from scipy.spatial import ConvexHull
import numpy as np

img = Image.open('image.png')
alphas = list(img.split()[-1].getdata())

region = np.argwhere(alphas)
region = [r[0] for r in region]
allVertices = [(i % img.width, int(i / img.width)) for i in region]

hull = ConvexHull(allVertices)
hullVertices = [allVertices[i] for i in hull.vertices]

print(str(hullVertices).strip('[]'))