Hi, so I have this image and it's very difficult to separate each particle. I have tried threshold but it didn't work out pretty well. Is there any other method that I can try to separate the particles and the background for better result?
Sorry for the late answer. I cannot see your image so you might want to upload it again.
That being said, what you are trying to do is usually called "segmentation". Have a look at the following helpful links (courtesy of @etarena):