Measure particle size for clustered objects

Hi All,

I am trying to analyze dimensions of large dataset of clustered objects using the “analyze particle” function.
Example image:

Does anyone have any strategies or plugins they could suggest?

Appreciate your help!


It was not clear to me, are you interested in the size of the size of the particles or the size of the aggregates?

Sorry if it wasn’t clear. I am interested in the size of individual particles

Is the raw image an RGB format?

Before converting to greyscale you can split the colour channels ‘Image → colour’. Using a different channel may help to highlight edges / individual particles.

I think much of it would be possible exploiting edge filters like the standard deviation filter. However, in some areas, the objects are actually overlapping, and no amount of filter based segmentation is likely to work. You might have better luck training a StarDist model or using CellPose. Either way, you may want to invert the image first so that the objects you are looking for are “bright.” But feel free to test it normally first!

I would suggest to use MorpholibJ and apply a watershed algorithm to seperate touching objects.

Before that you can apply some filtering routines. Here you find some resources:

If you have decent results you can count and measure the objects with the Particle Analysis of ImageJ.

By the way this topic has been discussed in this forum several times so you can search this forum
for watershed, particle analysis, touching particles, etc. to get some other examples.

Here are two more watershed plugins I found:

And here the built-in ImageJ watershed:

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Thanks for all the helpful suggestions @Bio7 and @Research_Associate . I’ll try out those options.

@FRANK -its not an RGB… its a phase-contrast image taken on a monochromatic camera

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