NORMALISATION background image

Hi everyone,
I was wondering, I have 4 different stacks of images (300 images each)
and I would like to quantify one staining put during the experiment.
However, for some stack, the background is a little bit different between each stack i’m not talking about each image in the stack, but between each stack!
I just want to reveal the intensity of my staining, the true one not playing with the contrast at all, but just to be able to compare all of them between each other!

So do you think playing with the threshold and put the threshold at 90 would be a good idea, so have a white background will be better.? or just try to normalise in the same way for each stack

Thank you so much in advance