Why an Atheist Thinks the Shroud of Turin is the Real Deal

Definition of an Edge

We need to clarify what we mean by an edge and we can use Russell table to illustrate this. Let’s just consider the top surface and forget about the legs, just to make things simpler. Assuming it is rectangular it has four distinct edges: front, back and two sides. But there may be more edges when it comes to examining the top and edge may not be the best choice of words for these other edges. Nonetheless, it is the word that is used in edge enhancement and so we will use it and define it better. Let’s imagine his brown table is brown because it is oak or some other form of wood. If we look more closely, we see the grain of the wood and everywhere there is a change from lighter to darker or vice-versa we have a visual edge. If you remove yourself to a distance the appearance of the wood’s grain will diminish and eventually disappear if you get far enough away. This is a phenomenon called visual blending. We will speak more about visual blending later.

Another phenomenon about edges and edge enhancement takes place in the retina. Some high quality Red Maple wood has a unique almost indistinct grain. The transition from lighter tones to darker tones in the grain is very smooth and from just two or three feet away it is almost unnoticeable. But back away from the table surface and the grain begins to appear. As the field of view increases, that is the desk takes up less of everything you see, the different shades of color in the grain are spread out across a fewer number of photoreceptors and edge enhancement kicks in. In other words the intelligence built into the retina begins to tell the rest of our brain that there is something there to discern.