Diffraction pattern spot intensity

Hi

Is there any way for ImageJ to identify the diffraction pattern spots (in white) and to obtain the raw integral intensities for them automatically, without manually selecting ROI for each of them and measuring? I’m having issues also as the “black” background is not 0 and inconsistent (ranges from 390-450), and hence would have to correct for the background as well.

diffpattern

Any help would be appreciated!!