In my quest to better my own lighting techniques by going back and working through lessons in various books and on websites, I've looked at apparent light size and the inverse square law. Both of these topics and exercises gave me a better handle on the three aspects of light as it relates to a subject: the lit portion, the shadow portion and the transition areas that fall in between.
However, to better understand all of this, I have to explore the lit portions of an object further, and that means looking more closely at what makes up the lit area of an object, namely, diffuse and direct reflections.
All objects produce a mix of diffuse reflection and direct reflection, and the amounts of each will change depending on the object itself. Shiny objects, black items and dark objects will often produce more direct reflection, whereas white, light colored and matte objects will often produce more diffuse reflection. Easy enough. To clarify all of this, though, it's beneficial to create some working definitions of the terms I'm using here. So let's have a look