A multilevel domain decomposition algorithm for fast O(N2logN) reprojection of tomographic images

A novel algorithm for fast computation of tomographic image projections is presented. The method comprises a decomposition of an image into subimages followed by an aggregation of projections computed for the subimages. The multilevel domain decomposition algorithm is formulated as a recursive procedure. The computational cost of the proposed algorithm is comparable to that of FFT-based techniques while it appears to be more flexible than the latter. Numerical results demonstrate the effectiveness of the method.