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Pore Size Distribution on a Scanning Electron Microscope
Image In this lesson Able Image Analyser will be used for
automated measurement of pore sizes in the SEM image "SEMPores.jpg"
(If you are using an old version of the program the image the image
is NOT included in the Sample images folder. Download it from here:
- Open file SEMPores.jpg.
- Perform spatial calibration: Spatial
calibration will calculate the conversion factor from pixels into
nanometers. It is described in the example Manual linear dimension
measurement. Correctly performed spatial calibration will reveal
that 1 pixel of the image represent 0.129 nm in the image.
- Cutting the image: We have to get rid
of the SEM information bar in the lower part of the picture. Use
selection tool to select the rectangle that includes just the SEM
image. Then use menu Edit - Copy and Edit - Paste as a new image
to obtain new image.
- Filtering: Because the SEM image is
noisy it has to be filtered a bit before further analysis. Use
menu Filters - Normal Filters - Soften (5x5) to reduce the
- Binarisation: The image has to be
binarized using thresholding procedure. Click menu
Binary-Threshold to show the intensity histogram. Click (and
drag) the left mouse button on the histogram to change the
threshold level. When the proper threshold is selected just the
pores should be colored red. A good threshold level for this
particular image seems to be around 70.
- Choosing parameters of analysis: Once
you have the binary image click menu Binary - Analyse Objects.
Set the minimum particle size to 200 pixels (to avoid analysis
ofsmall noisy chunks in the image) and maximum particle size to
1000000 pixels (to include big objects). Click OK.
- Analysis results: The program will
display outlines of all detected objects in the image and the
spreadsheet windows with analysis results for each objects.
The columns include:
- A: Object index
- B: X-Coordinate of the object center (in
- C: Y-Coordinate of the object center (in
- D: Size of the object (in square nm)
- Data export: The results of the
analysis can be exported to text file for subsequent analysis in
other programs, such as Excel, Origin, IgorPro, Mathematica,
Matlab... To export data click menu File -> Save As in the
spreadsheet window of AIA. Type in the file name and click OK.
- Data importis one-click away. In
Excel just use File -> Open to open the file. The spreadsheet is
prepared for further analysis.
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Analyser Worked Examples.