A search space expansion process is proposed in the context of tomographic reconstruction (TR). The idea is to widen the effective search space in a series of increasing sizes with clamping on the search space boundary. The technique was tested on four simple phantoms and on the clinically important Shepp-Logan phantom. Dispersive flies optimisation (DFO), a lightweight particle swarm optimisation (PSO) variant, is shown to produce lower reproduction errors compared to standard TR toolbox algorithms. The expansion technique demonstrably decreases salt-and-pepper noise. DFO with 50 subspace searches was found to be superior to differential evolution, PSO and, more importantly, a number of conventional reconstruction techniques. To the best of our knowledge, this is the first work where search space expansion, in its literal form, is introduced, discussed and applied to this problem.
CCS CONCEPTS• Computing methodologies → Continuous space search; • Theory of computation → Bio-inspired optimization.