Non-uniform resolution compensation in tomographic image reconstruction methods using median based priors

Penalized-likelihood (PL) image reconstruction methods produce better quality images than analytical methods. However, these images exhibit non-uniform resolution properties. A number of prior functions have been used to recover this resolution non-uniformity. Quadratic priors (QPs) are preferred for penalization due to their simplicity and their resolution characteristics have been studied extensively. Images reconstructed with QPs exhibit nonuniform resolution properties. Here, we propose two new priors based on QPs and median priors (MPs) and evaluate their resolution characteristics. The recovered resolution for the combined priors (CPs), which is a combination of QPs and MPs, can be set between QPs and MPs by selecting appropriate values for hyper-parameters. For new modified MPs (ModMPs), almost uniform spatial resolution can be achieved.