The positions of edges along each row and column of an NxN image are found by computing the singular value decomposition of a matrix formed with the 2N point 1-D Fast Fourier transform of a symmetric signal corresponding to the row or column and locating the peaks in the inverse of the sum of the absolute values of the 2N point Fast Fourier transforms of the left singular vectors corresponding to the group of smallest singular values of this matrix. The computational complexity of the proposed procedure is essentially 0(1V2log(N)).
A. H. Tewfik, A. H. Tewfik,
"Singular Value Decomposition Approach To Edge Detection", Proc. SPIE 1153, Applications of Digital Image Processing XII, (30 January 1990); doi: 10.1117/12.962325; https://doi.org/10.1117/12.962325