We are capable of discerning the individual elements of a scene because of the human mind’s ability to process the reflected light received through the eyes. Individual differences become apparent due to our relationship to the forms and their ability to reflect light. This is manifested as variations in color and value. The mountains stand out against the sky; the human head against the background; and so on. It is helpful to remember that everything we see is due to light. Without it, nothing visually exists. Painting is a representation of that light and is incapable of exact duplication. We are restrained by the limitations of the products we employ. We only create an illusion.
At the point of this perceivable separation, or where two objects meet, there is an area of transition. How this area is painted has the potential for either heightened luminosity or muddiness. It is common when painting these areas to represent each individually and then blend or smudge them together. If they are close in color relationship and near in value, this will work fairly well. But for most situations, this can be the recipe for mud or the loss of iridescence. When intermixed, the two areas clash, neutralizing one another. A better approach is to place a color and value between them that represents something halfway—a bridge (See the image, above, which shows an example of “bridging” color and value). If the areas share a common surface, it is best to bias the color choice toward the warm side, creating more of the glow of refracted light. Take, for example, a large area of sunlit golden grasses with a cast shadow falling across a section. The grasses fall into the yellow-orange color family at a high value, while the shadow has a dull violet tone in a low value range. If the edge where the two meet is simply rubbed or smeared together, a muddy gray is produced. If, instead, a middle value rose-red is minutely fused where they touch, a sense of luminosity is preserved. Cool colors, by nature, recede and work better when a recessionary transition is desired, like the edge of a tree next to a golden distant hill.
Don’t think of this as a trick, something overstated and cliché, but rather as a means of helping to represent the natural light which illuminates our scenes. Our job is to spend time observing and analyzing these transition points, and then to employ whatever means possible to represent the beauty of that perceived light.