Surface smoothing of 2D/3D objects

Yes MorphoLibJ - ImageJ you need to activate the site for morpholibJ. How to do it is explained in the linked page.

Hello! sorry for texting you repeatedly.
As you told me to perform several closing operations to make the outline smooth.
Should not I need to do an opening operation?
could you please tell me- Radius(in pixel mean)? is it the average radius of the particles?

My average radius is 6.22. If I put this value, surface not becoming enough smooth and fractal dimension is still so high. If I putrandomly higher value like 10, it gives me the desired fractal dimension.
Thank you.

I am not exactly sure what you are measuring and asking.
Concerning the operations:
Closing is a dilation followed by an erosion. So it will smooth out more the inside parts/indents of your objects.
Opening is an erosion followed by a dilation. This would remove some outer spikes and very small particles. Depending on what you want to achieve it could be that you want to apply both operations.

The radius has nothing to do with your particles. It refers to the structuring element. This is the region where you apply the morphological operation. Structuring element is an essential concept in image processing and you will find a lot of explanations on the WWW.

Are you computing the fractal dimension of each particle (the little blobs in the image you are showing ) or of the overall geometry (all the blobs I see in the image). A radius of the structuring element larger than your object may give whatever, up to completely disappearance of your particle if applied to a single particle. I guess it will over-smooth the data.

If you want to compute for each little blob you need to create a labelled image first and then analyze per blob.

I want to compute the fractal dimension of the overall geometry.

This is the image of ice crystals formed in the wheat-flour solution. I want to measure the fractal dimension of ice crystals (on average).
Thank you very much for your cooperation.