We have already said that, just as a sculptor reveals a composition by cutting away the unnecessary from a block of stone, a lighting designer, by extracting objects and figures from darkness, reveals a stage composition to the audience. In this sense, stage lighting creates a “stage vision.” This process of “stage vision” is multi-stage and complex, and not all of its steps are unambiguously understood or exhaustively studied. After all, to this day the nature of light is not treated unambiguously: as a compromise between competing theories, it is accepted as exhibiting “wave–particle duality.”
If we break down the process of “stage vision” into its components, we obtain the following sequence: some light source emits luminous energy; that energy, after reflecting from surfaces located on the stage and refracting in the eye, reaches the retina.
The retina transforms the received energy into electrical impulses via a photochemical mechanism; those impulses travel along the optic nerve to the brain, which in turn does more than simply read those signals — it interprets them in a specific way. It is very important to understand that these stages are not connected in a strictly linear fashion. The mere fact that the image formed on our retina is inverted, yet we nevertheless perceive it correctly, demonstrates that the incoming signals are interpreted by the brain at an unconscious level. This is a small but telling example; below we discuss features of perception in greater detail. For now, it is important to note that each stage of seeing depends on the mechanism of that stage. A light source emits energy which, in our context, is transformed in many ways before it reaches the viewer’s eye, governed by physical laws — reflection, refraction, transmission, diffraction, etc. — then, upon reaching the eye, it is transformed according to the physiological particularities of vision, and afterwards it is also interpreted by the brain, taking into account not only psychological but, as we will see later, social experience of the person we call the viewer. It is likely impossible for a lighting designer to study in depth every facet of psychophysiology of visual perception — that is the job of other professions — but knowledge of the main laws and characteristics of the full chain of the “stage vision” process will allow a designer to make better and more precise decisions in the search for means to achieve their goals.