Mahotas is a library of fast computer vision algorithms (all implemented in C++)
operates over numpy arrays for convenience.

Notable algorithms:
watershed.
convex points calculations.
hit & miss. thinning.
Zernike & Haralick, LBP, and TAS features.
freeimage based numpy image loading (requires freeimage libraries
to be installed).
Speeded-Up Robust Features (SURF), a form of local features.
thresholding.
convolution.
Sobel edge detection.
spline interpolation

Mahotas currently has over 100 functions for image processing and
computer vision and it keeps growing.