import numpy as np

a = np.arange(12).reshape(3, 4)
b = a.repeat(2, 0).repeat(2, 1)
print(b)

[[ 0  0  1  1  2  2  3  3]
 [ 0  0  1  1  2  2  3  3]
 [ 4  4  5  5  6  6  7  7]
 [ 4  4  5  5  6  6  7  7]
 [ 8  8  9  9 10 10 11 11]
 [ 8  8  9  9 10 10 11 11]]

>>> a = np.arange(12).reshape(3,4)
>>> print np.kron(a, np.ones((2,2), dtype=a.dtype))
[[ 0  0  1  1  2  2  3  3]
 [ 0  0  1  1  2  2  3  3]
 [ 4  4  5  5  6  6  7  7]
 [ 4  4  5  5  6  6  7  7]
 [ 8  8  9  9 10 10 11 11]
 [ 8  8  9  9 10 10 11 11]]

a = arange(1000000).reshape((1000, 1000)) # dummy data

from numpy.lib.stride_tricks import as_strided
N, M = 4,3 # number of time to replicate each point in each dimension
H, W = a.shape
b = as_strided(a, (H, N, W, M), (a.strides[0], 0, a.strides[1], 0)).reshape((H*N, W*M))