I used this methodology to segment bubbles in a liquid foam:

1. Preprocessing of the image aplpying median filter
2. Computing binary threshold using iterative Otsu method
3. Binarization of the image
4. Masking the binarizated image by labels = measure.label(binary, connectivity=2) props = measure.regionprops(labels)
5. detecting diameters of the images using prop.equivalent_diameter