Here is a list of several steps you typically need to go through with diffractGUI (see below) if you are after some more or less reliable results.
1 - Open input image
In order to demonstrate how diffractGUI operates, a sample image is provided and loaded by default. This allows you to just press
(2 - Optional: Set image resolution)
If the image contains information about the image resolution, it is loaded and you can see it in the
You can let diffractGUI to parse scalebars burnt into the image via
Note: Since scalebar contains many features rather attractive to the spot detector, it is advisable to detect the scalebar even if the image resolution is known. This allows to prevent the scalebar features to mix up with the image features and thus decay the results.
(3 - Optional: Adjust input image)
DiffractGUI allows you to slightly adjust the image using
If there is a region in your image, you do not want to be taken into account during the analysis (beamstopper, unwanted phase etc.), navigate to the main menu
4 - Select sample material
The sample material can be changed at any time during the analysis. Details about material database and selection can be found here.
(5 - Optional: Select analysis speed and type of diffraction pattern)
Although diffractGUI typically works all right with default parameters, you might like to adjust the analysis flow even though you are not familiar with the particular parameters. In this case, use two pop-up menus in the top right corner of
If you want to get your results fast or if you want to be sure about maximal precision, select appropriate option in
6 - Launch all
The whole analysis can be launched at once using the
6a - Find 30 strongest reflection candidates
Note: Right before this step, the image size is reduced if maximal allowed size image size is exceeded. The maximal size is set to 1024x1024px by default and can be changed in
In this step, diffraction spots are detected in several scales and 30 strongest candidates are selected. Number of the selected candidates can be adjusted according to the pattern nature. Detections can be also added, moved or removed manually after clicking at
Even though there is a considerable number of obviously misplaced or redundant detections (see the image aside), the final results can be all right.
Check: Press
6b - Fit the reflection candidates a lattice using RANSAC
RANSAC is a smart algorithm which fits a regular lattice to the detections even though they contain significant number of false detections.
Check: Press
6c - Pick nice lattice vectors
In this step, four lattice vectors in the regular lattice are found (see the image aside) and quantified in the panel
6d - Find zone axis
Now, the previously selected vectors are used to find the zone axis and to identify individual reflections. This is done by comparing the measured interplanar distances and angles with their theoretical counterparts. Those theoretical counterparts mean all planes of the given sample material having Miller indices lower or equal to the number stated in
Check: If you expect to face some weird "high-indexed" zone axes, make sure that maximal Miller index stated in
7 - Interpretation
Now it comes to the most important part ot the analysis, where we find how sound the results are.
If the image is nice, if you are sure about the camera length calibration, you know the sample material and you expect no tricky zone axes, then you can just keep the best zone axis found by diffractGUI and check the
In all other cases you need to check what the plot on the left and the the row of values on the right is telling you.
The plot is used to visualize how the theoretical d-spacings match with the measured ones. The dark-blue lines in the bottom part of the image correspond to the theoretical d-spacings specific to the sample material. The dark-blue lines in the upper part represent the d-spacings measured in the input image. The ligt-blue connector lines show the assignment required to obtain the zone axis selected in the



Nicely aligned - correct zone axis
Biased - camera length off
ZigZag - wrong zone axis
Furthermore, there are several important readings below the
8 - Save the results
If you need to save the results, you can generate an HTML report via