Segmentator v1.5.2

New features in version 1.5.x: Lasso drawing mode erase function is added to GUI. Deriche filter for determining the smoothness of the gradients. Useful for very high resolution data. Non-linear anisotropic diffusion based smoothing filters (Weickert 1998) are added as a new utility accessible through command line: segmentator_filters -h Fixes in the current version: Minor bugs related to gradient magnitude image exports. Updated links after publication of the paper and some readme cleaning