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I am creating a 2D DCT-II in labview but want to be able to check my outputs are correct. SciPy has a nice DCT function which defaults to DCT-II but is 1D.
I want to make it work for a 2D array. To do this the DCT must be applied to the columns and then the DCT must be again applied to the rows of this outcome.
I'm not sure what function I want to use to do this. I have tried np.rot90 which rotates the numpy array 90 degrees counter clockwise as follows:
import numpy as np
from scipy.fftpack import dct
a = np.array([[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0],
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0]])
b = dct(np.rot90(dct(a),3))
However this outputs the following:
array([[ 1152. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ -412.30867345, 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ -43.10110726, 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ -12.85778584, 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ 0. , 0. , 0. , 0. ,
0. , 0. , 0. , 0. ],
[ -3.24494866, 0. , 0.