Counting delustrants in fibers with ImageJ


Introduction

This week a collegue of mine felt the need to count the number of delustrants in a fiber. Wikipedia will explain you what delsustrants are.

A delustrant is a substance that reduces the lustre (sheen) of synthetic fibres.

The solution was to use ImageJ for this. It ain’t perfect but it’ll do.

ImageJ

First you have to download and install ImageJ (of course). I installed the 64 bit version with the Java 64 bit edition to go with it.I used version 1.43u.

Then we start it up. And we are met with a nice little screen like this.

We then open our file with File -> Open. This is a dark fiber so we decided to take the picture in darkfield to make the contrast between delustrants and fiber much bigger.

I then change the type to 8-bit grayscale via the menu Image -> Type -> 8-bit.

Now we have to Invert it via Edit -> Invert.

We now have to set a treshold. This is a bit tricky but very doable you just have to play with the sliders a bit to get the zones you want this will make the count much more accurate. We do this with the menu option Image -> Adjust -> Threshold…

Now we just have to Analyze -> Analyze particles. I changed the settings a bit to something that works best for this case.

And this is the result.

Conclusion

ImageJ works well for counting delustrants but you need some contrast between the background and what you are counting.

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