Fast progressive reconstruction of a transformed image (Corresp.)

Fast methods for performing progressive reconstruction of Fourier and Hadamard transformed images have been developed. Reconstruction of an
N \times N
point transformed image can be evaluated in order
N^{2} \log_{2} N
instructions. Accumulation of round-off errors due to iteration is reduced by the factor
(\log_{2} N + 1) / N^{2}
, compared with direct evaluation of the inverse transform.