Convolve two same size matrices using numpy

Question

I want to convolve two same-dimension matrices using numpy. According to the example on wikipedia this is a possible operation.

import numpy as np

f = np.array([[45, 60, 98],
              [46, 65, 98],
              [47, 65, 96]])

h = np.array([[ 0.1,  0.1,  0.1],
              [ 0.1,  0.2,  0.1],
              [ 0.1,  0.1,  0.1]])

print np.convolve(f,h)

console output

Why am I getting this error?

For 2D conv, look into scipy's version. Numpy's one is only for 1D. — Divakar
– Divakar, Commented Apr 5, 2016 at 10:02
makes sense, but scipy.convolve(...) gives the same output. So the problem lies somewhere else. — KilianK
– KilianK, Commented Apr 5, 2016 at 10:06

Francesco Nazzaro · Accepted Answer · 2016-04-05 10:23:07Z

3

try:

import scipy.signal
import numpy as np

f = np.array([[45, 60, 98],
              [46, 65, 98],
              [47, 65, 96]])

h = np.array([[ 0.1,  0.1,  0.1],
              [ 0.1,  0.2,  0.1],
              [ 0.1,  0.1,  0.1]])

print scipy.signal.convolve2d(f, h, 'valid')

It should implement the convolution described in your image.

The output is np.array([[ 74.5]])

answered Apr 5, 2016 at 10:23

Francesco Nazzaro

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