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22. Scipy Tutorial-图像的卷积fftconvolve

scipy的signal模块里提供fftconvolve可以对图像进行快速卷积运算，一般在图像的尺寸大于500时会很快，但尺寸较小的时候会慢一些。

#coding:utf-8

import numpy as np

from scipy import misc, ndimage,signal

import matplotlib.pyplot as plt

import scipy

print “scipy version is:”, scipy.__version__

src = misc.face()

print src.shape

misc.imsave(‘faceRGB.png’, src)

img = ndimage.imread(“faceRGB.png”, mode = “L”)

misc.imsave(‘faceGray.png’, img)

k = np.zeros((5,5))

k[1][0] = 1

k[4][2] = 1

k[3][4] = 1

img_con = signal.convolve(img, k, mode = “valid”)

img_fft = signal.fftconvolve(img, k, mode = “valid”)

if (img_con == img_fft).all():

print “same”

else:

print “diff”

plt.gray()

plt.subplot(221, title = “orginal”)

plt.imshow(img)

plt.subplot(222, title = “fftconvolve”)

plt.imshow(img_fft)

plt.subplot(224, title = “convolve”)

plt.imshow(img_con)

plt.show()

执行结果：