Fast two-dimensional Hartley transform
Ronald Newbold Bracewell, O. Buneman, H. Hao, John D. Villasenor · Proceedings of the IEEE · 1986
The fast Hartley transform algorithm introduced in 1984 offers an alternative to the fast Fourier transform, with the advantages of not requiring complex arithmetic or a sign change of i to distinguish inverse transformation from direct. A two-dimensional extension is described that speeds up Fourier transformation of real digital images.