ImageJ/Fiji
What is ImageJ? What is Fiji?
ImageJ is a free, java-based image processing software created by NIH developers. It has the ability to add plugins that can expand its capabilities. Fiji (which stands for Fiji is just ImageJ) is bundled with the most commonly used analytical plugins and those needed to open microscope file types (e.g. .lif, .czi).
Determining Fluorescent Intensity and Signal