Re: Power Spectrum Analyses in SPRING

[Carsten Sachse]

Dear Zhoaming,

On Dec 28, 2015, at 3:41 AM, Su, Zhaoming wrote:

Dear Carsten,

I have a quick question regarding the SegmentExam and SegClassExam. From your description in the tutorial it seems that the power spectrum from SegmentExam is the sum of power spectrum of each raw segment. Is this also the case for segment class average (i.e. the power spectrum from SegClassExam is the sum of segments from that class)? Or is it just the power spectrum of class average (one image)?

Yes, you are right: SEGMENTEXAM looks at the sum of the power spectra from individual segments whereas SEGCLASSEXAM shows the power spectrum of the class sum. You can also select for segments belonging to the class in SEGMENTEXAM by providing the spring.db file. In such a case, you should be able to double check that the power spectrum of the class is identical to the sum of the power spectra of the individual segments. As a consequence of the summation, in SEGMENTEXAM you will only have access to amplitude information whereas using the class sums you can also look at the phases using the interactive GUI version of SEGCLASSLAYER for example.

Best wishes,

Carsten

Best,

Zhaoming Su, Ph.D.
Postdoctoral Associate
National Center of Macromolecular Imaging (NCMI)
Baylor College of Medicine