visible filter in powerspectrum

Submitted by dhaselbach on Fri, 2015-09-18 05:28

Forums

Unblur & Summovie

Hello everyone,

using summovie with frame weightening with my frame data I seem to see the mask for weightening very strongly in the powerspectra. In other testdatasets from the empiar database I don't see this problem and I am wondering where this might originate from and wether this will be a problem in my further image processing as it appears to be rather sharp edges. I attached to exemplary powerspectra.

thanks kind regards

David

timgrant Fri, 2015-09-18 08:18

Hi David,

They do look a little weird. Could you tell me the pixel size, voltage, dose per frame and number of frames of these movies?

Thanks,

Tim

dhaselbach Fri, 2015-09-18 09:13

Hi Tim,

its 1.27 A/pixel, 300 kV, 3 electrons per frame, its 16 frames (originally 17 but the first is skipped).

thank you for your help.

David

dhaselbach Fri, 2015-09-18 11:42

Hi Tim,

I made an experiment it seems the problem arrises from the given dose rate. I made images from the same object with 1 , 2 and 4 electrons per frame. The higher the rate the more prominent the artifact. Further I tested with the same image stack just giving different dose rates and its has the same effect. The higher the rate the higher effect even if its always the same data.

I hope that can help you to find the problem.

Thanks again

David

timgrant Fri, 2015-09-18 14:48

Hi David,

When the dose per frame is high, then there can be a big difference in the filters between subsequent frames. The patterns you see in the final sum are essentially these big differences. I've been looking into it today, and at the moment I believe the program is behaving as it should, and although it doesn't look pretty i don't think it should be a problem for your refinement.

If you notice weird behavior that you think are due to these patterns - please let me know.

Tim