ENH: Add binary convex hull computation.

doc/examples/plot_convex_hull.py

@@ -0,0 +1,35 @@
+"""
+===========
+Convex Hull
+===========
+
+The convex hull of a binary image is the set of pixels included in the
+smallest convex polygon that surround all white pixels in the input.
+
+In this example, we show how the input pixels (white) get filled in by the
+convex hull (white and grey).
+
+A good overview of the algorithm is given on `Steve Eddin's blog
+<http://blogs.mathworks.com/steve/2011/10/04/binary-image-convex-hull-algorithm-notes/>`__.
+
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+
+from skimage.morphology import convex_hull
+
+image = np.array(
+    [[0, 0, 0, 0, 0, 0, 0, 0, 0],
+     [0, 0, 0, 0, 1, 0, 0, 0, 0],
+     [0, 0, 0, 1, 0, 1, 0, 0, 0],
+     [0, 0, 1, 0, 0, 0, 1, 0, 0],
+     [0, 1, 0, 0, 0, 0, 0, 1, 0],
+     [0, 0, 0, 0, 0, 0, 0, 0, 0]], dtype=float)
+
+chull = convex_hull(image)
+image[chull] += 1.7
+image -= -1.7
+
+plt.imshow(image, cmap=plt.cm.gray, interpolation='nearest')
+plt.show()