图像进行傅里叶变换后得到的图像是什么样的

function F = myDFT(f)[M,N] = size(f);Ur = 0:M-1;Uc = 0:M-1;WM = exp(-2i*pi/M);U = WM。^(Ur'*Uc)/sqrt(M);Vr = 0:N-1;Vc = 0:N-1;WN = exp(-2i*pi/N);V = WN。^(Vr'*Vc)/sqrt(N);F = U * f * V;end把上面的代码黏贴到matlab中,返回值就是变换以后的矩阵