1. A computer system capable of displaying and analyzing an image, the computer system comprising: one or more processors; one or more user input devices; a display capable of displaying the image and associated information in particular ways responsive to input signals from one or more of the input devices and signals from one or more of the processors, wherein the image comprises a photographic representation of an object superimposed with a light emitting representation of the object, the light emitting representation corresponding to the location and magnitude of electromagnetic radiation emitted from the object; and a graphical user interface running on one or more of the processors and providing, on a single display window, the image and one or more tools for defining a region of interest on the image, wherein when a user uses one of the tools to define a region of interest, the computer system can calculate information about a portion of the image within the defined region of interest.