Hi I need to compute the fft of an image A with dimension (Nx,Ny) and are not sure on how to compute the wavenumber. I have done like that but i am not sure i am computing the wavenumber in the correct way..can someone help? sara image.plot(x,y,A) dx = diff(x)[1] dy = diff(y)[1] ## This is equivalent to what the matlab fftshift function does fzs = fft(A) Fzs = fftshift2D(fzs)/(Nx*Ny); ## compute the wave number for the shifted fourier transform k = seq(-pi/dx,pi/dx,length.out=Nx); l = seq(-pi/dy,pi/dy,length.out=Ny); [[alternative HTML version deleted]]