We might be able to help if the droplets are all separated in your image. I have worked on several spray problems in the past. If your image is not good then you might have to alter/improve your image capture conditions, or else measure something else that is relevant, like area fraction or whatever.
It's a generic, general purpose demo of how to threshold an image to find blobs, and then measure things about the blobs, and extract certain blobs based on their areas or diameters.
If you have any more questions, then attach your image(s) with the paperclip icon after you read this:
