Hi Jianhua,
We see this artefact also sometimes, but you do not need to worry about
it. Probably it has to do with correlations "spilling over" into the next
(1 or sometimes 2) resolution shell(s) after the phase-randomization,
leading thereby to an over-correction. We sometimes just omit that point
from the corrected curve. Perhaps I'll do something along those lines in
the next release. You should of course be very suspicious if the entire
corrected curve drops rapidly after the phase randomization, but just a
dip of 1 (or 2) shell(s) is OK. In your case, I would be more worried
about the corrected curve having a plateau that is much lower than the
near-1 value just after this dip. Are you sure your mask is not too tight?
We often put a soft edge of up to 10 Angstroms on our masks.
HTH,
S
> Hi Sjors and Relion users,
> I was curious as to what the 'corrected' FSC generated from Relion
post-processing means. The attached image shows FSC curves after
post-processing: one with just masked maps and the other is the
> corrected FSC. The corrected FSC shows a local minimum around the
resolution where phase randomization started. I didn't see this effect
in Chen et al, Ultramicroscopy 2013. What's causing the FSC dip and do
we need to worry about this?
> Best regards,
> Jianhua
--
Sjors Scheres
MRC Laboratory of Molecular Biology
Francis Crick Avenue, Cambridge Biomedical Campus
Cambridge CB2 0QH, U.K.
tel: +44 (0)1223 267061
http://www2.mrc-lmb.cam.ac.uk/groups/scheres
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