Absolutely-scaled electron density maps for more accurate signal
True noise maps to help clear the fog

END maps place electron density on an absolute scale (e⁻/ų), where zero corresponds to vacuum rather than the average density. RAPID maps show the true noise level at every voxel—typically 6–8× lower than the conventional 1σ threshold.

Source code on GitHub
Shell scripts (tcsh/CCP4/Phenix) and a Python port (phenix.python/cctbx, no CCP4 required)

Download: end.rapid.tar.gz  •  Documentation  •  Manual

Citing END/RAPID: Lang PT, Holton JM, Fraser JS, Alber T. “Protein structural ensembles are revealed by redefining X-ray electron density noise.” PNAS USA. 111:237–247 (2014).