FAQs

Preprocessing

• Do I need to downsize my images?
  • RELION will estimate the resolution of your model and downsize the images internally. Therefore, using downsized images will NOT be much faster than using large images. The only reason why one would want to downsize images if they are very big (e.g. 800x800 pixels) and the reconstruction(s) would not fit into memory.

Classification

• Should I refine my 3D classes in a different program to reach higher resolution?
  • This is not necessary: you may do so in RELION. Higher resolution often means using fine orientational and translational samplings, which may be prohibitive (speed and memory-wise) inside classification runs. One can however write out a new STAR file that contains only the images belonging to a certain class. That STAR file could then be used for a single-reference refinement with fine samplings in RELION. The following awk command may be used to select class number 3 (assuming rlnClassNumber is the 13th column:

awk '{if (NF==1) {print} else {if ($13==3) print }}' < classify_it000025_mlmodel.dat > class3_only_input.star