Knowing that DFT of n-values real signal in 1d consists of n/2+1 different values where the second half of the spectrum is complex conjugate of the first one (Hermitian symmetry).
However in the spectrum of 2d signal that I've made in Octave I see complex conjugates in both dimensions. However the FFTW manual states that we can take a use of the symmetry in only one dimension.
What is the truth? Is Hermitian symmetry only useful in one of multidimensional transform or could it be used in other dimensions?
Ok, so since the Hermitian symmetry occurs in each of the directions then why the transformed vector in FFTW is diminished only by half (only one dimension values are stored on N/2+1 complex numbers)? Why isn't each direction diminished?