Re: [scipion-users] pixel size; CTF binning

[Carlos O. S. <co...@cn...>]

Dear Dmitry,


On 02/08/17 12:09, Dmitry Semchonok wrote:
> Dear colleagues,
>
> 1.
> I have a problem with the data - the pixel size of 1 data set is 
> different form the 2nd one.
>
> Does anyone know how to *change the pixel size* of a *movie stack 
> before* adding it to the project? Any software?
At this moment, you cannot change the pixel size at the level of movie 
stack, but you can when extracting the particles. At that point you can 
make both datasets to have exactly the same pixel size.
>
> (I know that on the particles level we can use *xmipp - crop/resize 
> particle* script but I rather want to avoid that)
>
> The idea is to combine 2 data sets in 1 folder (after pixel 
> equalization) and then
> add it to the  SCIPION project.
If you do it from the command line, you may try

xmipp_image_resize -i inputMovie.mrcs -o outputMovie.mrcs --factor 1.02

where the factor 1.02 is the ratio between the two sampling rates.
>
> 2.
> About the CTF binning.
>
> Let say you binned your CTF estimation to 2.
> Is the 2ce binned CTF estimation is more reliable and still describes 
> the higher frequencies?
> Or no binning is preferable?
No binning should be preferred, as long as the Thon rings are 
sufficiently visible so that the estimation can be reliably performed, 
for instance, if the Thon rings are too concentrated at the origin, then 
the estimation may go wrong.

Cheers, Carlos Oscar
>
>
> thank  you.
>
>
> Sincerely,
> Dmitry
>
>
>
>
>
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Carlos Oscar Sánchez Sorzano                  e-mail:   co...@cn...
Biocomputing unit                             http://biocomp.cnb.csic.es
National Center of Biotechnology (CSIC)
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