[chimerax-users] Interactive map sharpening and filtering?

[Aaron Lewis]

I'd add that there is an important difference between Gaussian filtering
and band-pass filtering: Gaussian filtering blurs (sharpens) everything by
a specified amount, whereas low-pass (high-pass) filtering imposes a
minimum amount of blurriness (sharpness). This often makes band-pass
filtering the right choice for images with heterogenous resolution, because
you often want to blur the noisiest, sharpest parts without blurring the
smoothest, blurriest parts. Cryo-EM maps often fall in this category, and
thus represent a common use case.

On Wed, May 10, 2017 at 2:54 AM Tom Goddard <goddard at sonic.net> wrote:

> This is just like ChimeraX Gaussian filtering which does a convolution
> with a Gaussian in Fourier space.  That is relatively fast — a few seconds
> for a 256**3 map.  You can already do sharpening with the “invert” option
> to the gaussian filtering command (“vol gaussian #1 1.5 invert true”).
> Gaussian filtering is one form of low pass filtering — others could be
> added.  I think it would be nice to allow a very fast (10 updates per
> second) test filtering on a small region using a mouse drag to figure out
> the desired parameters.  But I never spent to the time to figure out a user
> interface (what small region, how do you undo, how do you then apply to
> full map, …).
>
>         Tom
>
>
> > On May 6, 2017, at 10:27 AM, Oliver Clarke <olibclarke at gmail.com> wrote:
> >
> > Hi,
> >
> > Has any consideration been given to adding the capacity for
> fourier-space map sharpening/low pass filtering to ChimeraX? I’m not sure
> whether or not it is feasible speed wise, but if it is it would be a very
> useful addition for EM, allowing one to easily try different sharpening
> B-factors/low pass cutoffs and save the resulting map(s).
> >
> > Cheers
> > Oli
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