This is an implementation of (part of) the algorithm described in Condat et al. Reversible, fast, and high-quality grid conversions, IEEE Transactions on Image Processing, vol. 17, no. 5, pp. 679-693, May 2008. It transforms data sampled on a hexagonal grid, such as an X-ray detector with hexagonal pixels, into a conventional cartesian lattice.
Specifically, it implements what that paper describes as a Type II fractional delay filter, with N=2.
This package is based on code written by Andreas Scherz and Rafael Gort.