Implementing dhash with numpy and skimage.

gistfile1.py

import numpy as np
from skimage.data import imread
from skimage.transform import resize
from skimage.color import rgb2grey

"""
http://www.hackerfactor.com/blog/?/archives/529-Kind-of-Like-That.html
"""

TWOS = np.array([2 ** n for n in range(7, -1, -1)])
BIGS = np.array([256 ** n for n in range(7, -1, -1)])


def dhash(picture):
    img = rgb2grey(resize(picture, (9, 8)))
    h = np.zeros([8], dtype=np.int64)
    for a in range(8):
        h[a] = TWOS[img[a] > img[a + 1]].sum()
    return (BIGS * h).sum()


def dhash_hex(picture):
    img = rgb2grey(resize(picture, (9, 8)))
    return ''.join(["%02x" % TWOS[img[a] > img[a + 1]].sum() for a in range(8)])