python遍历输出图片_在Python中循环遍历图像的每个像素的更快方法？

I need to loop through each pixel of a 2560x2160 2D numpy array (image). A simplified version of my problem is as follows:

import time

import numpy as np

t = time.clock()

limit = 9000

for (x,y), pixel in np.ndenumerate(image):

if( pixel > limit )

pass

tt = time.clock()

print tt-t

This is taking an obnoxious ~30 seconds to complete on my computer. ( Core i7, 8GB ram )

Is there a faster way to perform this loop with an interior 'if' statement? I am only interested in pixels above a certain limit, but I do need their (x,y) indices and value.

解决方案

Use a boolean matrix:

x, y = (image > limit).nonzero()

vals = image[x, y]