When artists talk about the value of a painting, they may not mean the price. They may be talking about the widespread use of light and dark shades on canvas.
The value of any color is a relative evaluation of how light or dark it is. A color with a low value will be very dark and one with a high value will be light. Putting a very dark color next to a very light color creates high contrast, and putting two colors next to each other with similar values creates low contrast. An extreme example of low contrast would be painting an entire canvas in one setting, even if it is painted in many colors.
Maybe we are looking at a scene from San Francisco and it is a very foggy day. One of the ways an artist is going to convey that gray urban landscape is to develop a composition in which the value of all the colors within the painting is quite similar. In this painting there may be colors with distinctly different hues, for example a medium-toned cobalt blue and a deep-toned crimson red, and yet they could be roughly the same value. The challenge for the new student is to discern the value of different colors.
Value is important for painting because its variations create attributes such as depth, texture, volume, distance, light source, focus points, and mood.
That is why it is important to learn to know the values of the colors that are used. There are several ways to develop a sharper sense of worth. The simplest is to squint while looking at the subject or put on a pair of sunglasses. The more we squint, things get murkier and the richness of all colors disappears from our sight. Our eyesight becomes more black and white and the true values, brightness or darkness of all colors become more apparent. A blue, a dark red and a green can have the same value.
To truly test your sense of worth, try this simple and insightful lesson. Take a wooden cube or any cube where all the sides are the same color and place it on a piece of cardboard. Then shine a light from an angle so that the cube casts a shadow and has both light and dark faces. Paint three different studies of that cube. In each study, use different colors to paint the various faces of the cube, as well as the shadow that is cast, but do your best to match each color to the value of the degree of lightness or darkness of the individual sides of the cube.
You now have three paintings from that bucket with a totally different color palette, but hopefully three paintings where the value variations are exactly the same. To see how well each of the paintings took and made a black and white copy on a Xerox. When producing a black and white copy, it reduces all colors to their true values. All three copies should look exactly the same, but don’t be disappointed if they don’t! Practice will bring you closer.