Fastest code C/C++ to select the median in a set of 27 floating point values

Question

This is the well know select algorithm. see http://en.wikipedia.org/wiki/Selection_algorithm.

I need it to find the median value of a set of 3x3x3 voxel values. Sinc

Answer 1

Since it sounds like you're performing a median filter on a large array of volume data, you might want to take a look at the Fast Median and Bilateral Filtering paper from SIGGRAPH 2006. That paper deals with 2D image processing, but you might be able to adapt the algorithm for 3D volumes. If nothing else, it might give you some ideas on how to step back and look at the problem from a slightly different perspective.