What makes an object look three-dimensional? We use a variety of cues to give us this information: light and shadow, contrast, pattern, color, texture, scale, temperature and value, usually in combinations. Our ability to measure these different parameters and make a decision about the dimensionality and location of something in our field of vision is automatic and immediate – a product of millions of years of evolving visual sophistication.
|Black and white and full-color versions of Monet's Regatta at Argenteuil, oil painting.|
In drawing, we learn to create the illusion of form with value changes (light to dark), or chiaroscuro, using all the subtle changes in tone from black to the white of the paper. Having gained proficiency at chiaroscuro work, we quite naturally adapt our knowledge of values to our color work. But the world of colors is not just value-driven. It has an equal partner in color temperature. Temperature (warm to cool) can and does affect our perception of form. As the shape of any object turns away from the light source, it undergoes a temperature change. It may also display a value change, but in some situations, such as an overcast day, dusk, pre-dawn, or a dimly lit interior, light conditions are not intense enough to create significant value changes in an object. However, we are still able to perceive three-dimensional form partially because we can perceive temperature changes.
The Impressionists loved to exploit this effect. Temperature changes were an essential ingredient in their ability to create scintillating, light-filled canvasses. They thoroughly understood the power of temperature changes within a limited value range in reproducing the effects of sunlight. Cezanne and Monet especially, triumphed at these kinds of techniques, so much so that most people aren't aware of the missing values. See how these black and white conversions of their paintings reveal their mastery of temperature within a restricted value range.
|Cezanne's Still Life with Bottles and Apples
in black and white and full-color.
The best way to understand and learn how to use temperature instead of value to create three-dimensionality is to set up a simple still life. It must be noted that we can't ever get completely free of some small value changes. Because the nature of paint, unlike light, is subtractive, every time we mix two colors together (other than white), the paint mix darkens some. When we try to compensate for that value shift by adding white, we cool the temperature of the mix by the amount of white added. If we are trying to maintain a warm temperature with the mix, we are now fighting the process, and the paint will always win. The answer is to plan our temperatures so that the lightest, warmest color does not require white, and the rest of the object is painted cooler and very slightly darker as it turns.
This is one of the great secrets of the masters! Try this yourself and you'll be amazed at how easy it is to create a convincing three dimensional world from a limited value range. To see more on this subject, including two painting demonstrations of this principle, join us on The Artist's Road.
–John & Ann