Application of orthogonal elements in a-priori reconstruction: Fourier and polynomial techniques

The mathematical setting assumed is the Hilbert space. Two image reconstruction problems are summarized. In one (from emission tomography), an unknown member, f, of the space is sought as a linear combination of linearly independent elements g/sub 1/, g/sub 2/, . . ., g/sub n/, under the hypothesis that the inner products are known for 1>