Image restoration for space invariant pointspread functions

We show how to apply a truncated eigensystem expansion in the solution of image restoration problems for the case of space invariant point spread functions. The solution is obtained directly from the system of linear equations, which result from the discretization of the Fredholm integral equation of the first kind. Fast Fourier transform techniques are used in obtaining this solution. A procedure is devised to estimate the rank of the coefficient matrix that gives a best or near best solution. It is demonstrated that this algorithm compares favorably with other existing methods. Numerical results using spatially separable point spread functions are given.