A series of images focusing on the plaster cast or a similarly one-toned object. I'm looking at the line that separates shadow from light and focusing on it. There's a surprising amount of range that can be gotten out of very few values if the focus is placed on the relative difference between the values, rather than their absolute values. For example, if two values are very near each other, and a third is quite different, the overall range of the three values is less significant --to a certain extent-- than the overall range they occupy. Another way of putting it would be to say that both the absolute range and the relative range are of exactly equal importance, but the eye sees the absolute through the relative, and picks out the differences within a pre-established range of values.