Is there an easy way (i.e. free or open source tool) to determine the spatial color distribution (i.e "intensity") in a picture or in a region of interest of this picture?
Let's say I used a laser or some lenses and mirrors and a light bulb to adjust a ray of light on a piece of paper in a dark room and photographed the spot and now I want to find out the rough intensity distribution, e.g. if it is a flat distribution or a gaussian or something else.
With what tool is this possible?