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Jitterbug is a piece of STEM image correction code, written in MatLab™, for the identification and correction of image distortions and drift. Distortion can be common in recorded STEM images and degrade signal-noise (SNR) or resolution performance. Compensating for these distortions can recover much of the lost performance and the code has so far demonstrated improvements of SNR and resolution of up to 42% and 10% respectively. Academic/non-commercial users can now Download Jitterbug for FREE.

Main Features

The current v3.6 release includes several new features. Now from a single STEM image the Jitterbug code can:

• Identify and compensate for horizontal and vertical 'scan noise',
• Measure sample or stage drift during acquisition and correct for it,
• Calculate the probe's distortion frequency spectrum and identify the five strongest peaks,
• Quantify the resolution and signal-noise ratio of the raw and restored images.

Demonstration Video

Example 'Before and After' Results

Example STEM ADF image (top) and the associated Fourier Transform (bottom), restored using the Jitterbug post-processing software.

Scanning transmission electron microscopy (STEM) can be affected by the effects of environmental instabilities because of the technique's serial acquisition recording. Any time varying disturbance such as acoustic or seismic vibrations or electrmagnetic fields can disturb the image recording process. The purpose of this image-processing code is to detect and correct for such image distortions.

The example below show an enlargment from a section of a STEM HAADF image from [100] oriented Strontium Titanate (STO).

In the as-recorded image many atom columns appear sliced horizontally. In addition some atoms appear to have dissociated rows above or below their main form. In the restored image the image rows of each of the atom columns are brought back together. Additionally the image shear imparted from sample/stage drift has been corrected such that the lattice planes once more appear perpendicular as expected. In the example (left) the Jitterbug restoration code improved SNR and resolution by 30% and 13% respectively

In the Fourier Transform (FT) of the as-recorded image there are two strong bands running vertically that arise from the scan noise as well as streaking of the Fourier spots. In the restored FT these band are greatly reduced as well as the spot streaking. The drift compensation is also evident in the FT where, after reconstruction, FT spots are correctly at ninety degrees from one another.

A full-length manuscript describing this work was published in the journal Microscopy & Microanalysis and can be downloaded here.

User Consoles & Output Displays

While Jitterbug is running there are various displays of the progress. This allows the user to check that the restoration is proceeding as expected or watch for the signs of incorrect input variable choices.

During the main restoratrion phase, the horizontal-distortion correction, the following display is shown:

The main console shows three panels. The top-left plot shows the distortion profile detected for each image row as this is processed. This plot shows the determied value of the probe offset as a function of time. The top-right figure shows the image as it is processed with the area above the line having already been processed. The larger bottom plot shows the frequency spectrum of the distortion. This is the average distortion across all the rows prcessed so far and so is updated each time the console is redwrawn and becomes less noisey and more reliable the more rows that have been processed.

During the restoration a progress bar shows the progress and a new, more accurate, estiamte of the time remaining. The restoration requires no user input when running so can be left running in the background until complete.

After the restoration is complete a results summary window is displayed. The window shows the before and after signal-noise ratio (more is better) as well as the before and after resolution (smaller is better). The strenght of the drift before and after correction is also displayed (smalle is better).

Download Jitterbug

Research users can now Download Jitterbug for FREE.

Content © 2012 Lewys Jones - layout & design by Vincent Chan