Computes the 2D discrete Fourier transform (DFT) of this matrix. The
physical layout of the output data is as follows:
this[k1][2*k2] = Re[k1][k2] = Re[rows-k1][columns-k2],
this[k1][2*k2+1] = Im[k1][k2] = -Im[rows-k1][columns-k2],
0<k1<rows, 0<k2<columns/2,
this[0][2*k2] = Re[0][k2] = Re[0][columns-k2],
this[0][2*k2+1] = Im[0][k2] = -Im[0][columns-k2],
0<k2<columns/2,
this[k1][0] = Re[k1][0] = Re[rows-k1][0],
this[k1][1] = Im[k1][0] = -Im[rows-k1][0],
this[rows-k1][1] = Re[k1][columns/2] = Re[rows-k1][columns/2],
this[rows-k1][0] = -Im[k1][columns/2] = Im[rows-k1][columns/2],
0<k1<rows/2,
this[0][0] = Re[0][0],
this[0][1] = Re[0][columns/2],
this[rows/2][0] = Re[rows/2][0],
this[rows/2][1] = Re[rows/2][columns/2]
This method computes only half of the elements of the real transform. The
other half satisfies the symmetry condition. If you want the full real
forward transform, use
getFft2
. To get back the original
data, use
ifft2
.