擅长:python、mysql、java
<p>更简单且更快的解决方案:使用SciPy的<a href="https://docs.scipy.org/doc/scipy-0.15.1/reference/generated/scipy.ndimage.filters.uniform_filter.html" rel="nofollow noreferrer">^{<cd1>}</a></p>
<pre><code>import numpy as np
from scipy import ndimage
rows, cols = 500, 500
win_rows, win_cols = 5, 5
img = np.random.rand(rows, cols)
win_mean = ndimage.uniform_filter(img, (win_rows, win_cols))
win_sqr_mean = ndimage.uniform_filter(img**2, (win_rows, win_cols))
win_var = win_sqr_mean - win_mean**2
</code></pre>
<p>“跨步技巧”是漂亮的技巧,但4慢,不可读。
<code>generic_filter</code>比跨步慢20倍。。。</p>