[Freesurfer] complex numbers overlay, colour wheel interpretation

Dear all

I realised that freesurfer can handle overlays of complex numbers (e.g. as given by a fourier analyis) when they are split up in two separate volumes: one containing the real and the other containing the imaginary part of each voxel ("complex numbers" flag in the overlay configuration menu). It seems that freesurfer is able to read out the phase angle for each voxel and to depict different phases as different colours. However, unfortunately, when using the colour wheel, I haven't managed to figure out yet what colour corresponds to what phase (I assume the angles range from pi to -pi).

Does anyone know how to interpret the colour wheel in that context?

Many thanks, anyway

best wishes

Andreas