Hi. I'm still new on ImageJ so my question might seem silly !!! I'm trying to determine the intensity of the fluorescence of a whole image ( not in a single cell). I've read many ways and that makes me more confused in what method I should apply. In one method, I can directly choose the whole images and then go to analyze-measure and I can measure the intensity. But also I read that I its better to adjust the image threshold and then do the analysis and in other comment , it said that I can select the histogram from the analyze menu. I'm confused as in what is the best way to analyze the florescence intensity and is there any specific equation that I should apply to correct for background effect.

Really thanks if you can help me in this,
Nour