I’m not certain which is your signal of interest. My wild guess at the moment would be to try the module “EnhanceOrSuppressFeatures”. If you’re interested in little dots, try option Enhance > Speckles > Size of object-of-interest is about 5 px or less.
If none of the options in EnhanceOrSuppressFeatures would help you, then I suggest to try any other modules that has that kind of “window probe”, where you basically screen the whole image and only enhance the objects that fits into the window-size and ignore the bigger regions, i.e. background.
Maybe that might help. But again, higher quality images should serve you better than these tweaks.