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Category: Data Processing and Evaluation – Images
Description: Script to compute a periodogram from the active image, using the Welch method (averaging pieces.) Also does a rotational average of the sq. modulus, outputting the data to a .csv file and a Gatan line profile. It writes the spatial frequency in the units 1/A. I installed the script to a menu item; also runs from the script file.
Comments: Uses values stored as tags for repeated use. Defaults are set by the script. I edit these with the Tag editor. I understand the form of these tags changed in v. 1.6 This is a bug fix than handles the loops correctly.
Acknowledgements: Uses ideas from HanningFFT.s by Ruben Bjorge of NTNU and especially P. D. Welch et al., "The Use of Fast Fourier Transform for the Estimation of Power Spectra: A Method Based on Time Averaging Over Short, Modified Periodograms", IEEE Transactions on Audio Electroacoustics, Volume AU-15 (June 1967), pages 70-73 Also uses ideas from the Gatan Scripting section of the DM User Manual
Script version: 2.0
DM/GMS version: 1.8
Script written as a function: Yes
Source: Show code
Download Source Code: Download
Download Zip File: Download