This site is being phased out.

# Analysis of SEM images of alloy

Question: The image "is an SEM of a special alloy. My objective

• 1-Identify the amount of each separate phase, ie the dark particles, the lighter particles and the lighter area
• 2-Determine how many particles of each type there are by some size limits. You can see some are quite large and some are quite small.
• 3-Identify the location and size of given particles."

The second image is "taken with a digital microscope of metal particles.

• 1-Want to find the number of particles by various size limits
• 2-Identify the location and size of given particles
• 3-In this sample, I was not able to get the background noise suppressed in the areas without particles.
• 4-Grab and move particles to an area of the photo, that is physically sort by some of the type, ie long, crooked etc."

I start with the second image as it's of better quality. I analyzed it and the results seem OK (consider some issues though). The results are displayed.

Since the images are fairly small you don't have to shrink them. Just set the factor at 1. I set it at 2 to speed things up. The image are also virtually gray scale, so all color channels are the same and there is no need to choose one. (More on these issues: Image scaling and RGB channels.)

>>I thought the location codes were the location of the particle, but the explanation=the center of the object as a lamina of uniform density is not clear what this means.

Since we can't see the actual thickness of these particles in the 2D image, we have to make the (mathematical) assumption that the outline of the particle in the image is its shape and its thickness is uniform. That's a "lamina". We use then its geometric center as the location of the particle, i.e. centroid. The coordinates of this point appear in the output table: Location X and Location Y.

The column that follows the location contains the sizes (areas) of the particles. If you push "Save table" an Excel report is created. You can then use Excel's capabilities to create the histogram of the sizes of the particles, like the ones presented here: Report generation and here: Image statistics.

Even without the background noise suppressed in the areas without particles, it seems to have worked out fine.

>> 4-Grab and move particles to an area of the photo, that is physically sort by some of the type, ie long, crooked etc.

There are no capabilities like this at this time. The closest to this is to create a histogram of the particles with respect to their "roundness".

The second image isn't as good: the gray level varies a lot, even within the particles, and there is virtually no background. In fact, I'd find it hard to outline them even by hand.

The best I was able to do is to get the total area of the particles, 62%, below:

As you can see thresholding was used.

See other examples of image analysis.