In the local basis-function approach, a reconstruction is represented as a linear expansion of basis functions, which arranged on a rectangular grid and possess a local region of support. The basis functions considered here are positive and may overlap. It is found that basis functions based on cubic B-splines offer significant improvements in the calculational accuracy that can be achieved with iterative tomographic reconstruction algorithms. By employing repetitive basis functions, the computational effort involved in these algorithms can be minimized through the use f tabulated values for the line or strip integrals over a single basis function. The local nature of the basis functions reduces the difficulties associated with applying local constraints on the reconstruction values, such as upper and lower limits. Since a reconstruction is specified everywhere by a set of coefficients, display of a coarsely represented image does not require an arbitrary choice of interpolation function.
Keywords: limited-angle tomographic reconstruction, local basis functions, cubic B-spline basis, image visualization, image interpolation, Algebraic Reconstruction Technique (ART), strip integrals for projection and backprojection
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