Hi there,
I was wondering if anyone can tell me how to quantify fluorescence
intensity with image J. I don't need to analyze single cells, I just want to measure the fluorescent intensity of an image (or selected area of an image) and compare with others taken under same conditions.
According to the protocol I know that I have to do the following:

1. Convert the color picture to 8it-b black and white scale.
2. Subtract the background fluorescence equivalently for all images by setting the threshold to 50% maximum intensity.
3. To quantify the mean fluorescence
I will appreciate if someone can post a tutorial with screen-shots regarding my question.

Thank you in advance for your help