Option for frame off-set in Summovie

Submitted by nfischer on Fri, 2015-07-10 07:49

Forums

Unblur & Summovie

Dear all,
I have a question how to deal with image stacks which start after a pre-exposure, i.e. the first frame aquired by the camera is not included in the saved stack.

A not very elegant and time-consuming solution would be to duplicate the first frame and put it in front of the stack. Summovie would then allow to omit this first frame from the sum and to use the appropriate dose-filter. However, it would be much nicer to be able to define an off-set and to tell Summovie that the first frame is missing in the stack to allow correct dose-filtering. I guess this will be an issue for many people using the Falcon II hacking tool when discarding the first frame which contains the opening beam shutter.

Thanks a lot for any help
Niels

timgrant Fri, 2015-07-10 10:09

Hi Niels,

This is a good idea, I will add such an option to the next versions - which will hopefully be available sometime next week.

Until then, I think that if the pre-exposure is fairly small, and all images have the same pre-exposure you should be able to just ignore it in the current version and the relative weighting of the frames should be basically correct, even if the absolute weighting is not.

Tim

nfischer Wed, 2015-07-15 10:41

Hi Tim,

just a follow-up question. I guess a pre-exposure by <1e-/A^2 will not change much in terms of the dose filter. However, will it still be neglectible for - in my case - a pre-exposure of about 2.7 e-/A^2 ?

Thanks in advance for any estimate and best regards
Niels

timgrant Fri, 2015-07-17 18:11

Hi Niels,

I guess it depends on the resolution - the higher the resolution the more difference it will make. My guess, is that it won't have a huge effect, but I am not 100% sure.

At any rate - the new versions are available for download now, they add the option of saving aligned frames to unblur, and the option of a pre-exposure to both unblur and sum movie.

Let me know if you have any problems!

Tim

nfischer Tue, 2015-07-21 02:51

Hi Tim,
thanks for implementing the pre-exposure option so promptly!

Best regards
Niels