Value is the relationship of one part or detail in an image to another part of the image with respect to either the lightness or darkness of those parts and details.
Often, we get so caught up in color we forget that without value, there would be no color. A piece of art with the correct values in the right places will be understandable even if the color is wrong. The reverse is not necessarily true. Occasionally when working on your art, convert your piece to a grayscale image. Does it still hold up visually? If you are being too influenced by color, you will quite clearly see problem areas caused by the lack of value patterns.
Most of us already know what value is. The problem comes in knowing what to do with it. The careful use of value can help you create dramatic, meaningful, and easily understood visual images. Misuse of values will lead to the viewer's visual fragmentation and confusion.
The principles of using value are the same for traditional art and computer art. In either medium, value can do three things for you, the artist, either individually or in combination: the description of objects, the expressive, and the decorative .
The most common use of value is the description of objects. We see the world around us because of the patterns and shapes created on and by objects when light falls on them. These patterns and shapes are simply the light and shadows that we see. Figure 7.2 shows a group of simple objects that are seen because of their value differences.
There are only two kinds of shadows: form shadows and cast shadows. Form shadows are the most useful for the artist because they describe the light and dark sides of objects. Everything we see has parts that either face the light or not. The transition from the light to dark can be gradual on curving surfaces or abrupt on angular surfaces. In general, the more gradual the turn of a form, the softer the shadow will be. Cast shadows are pretty easy to understand. If something gets between an object and the light source, it will cast a shadow. Figure 7.3 shows both cast and form shadows.
Each shadow gives us the visual cues we need to recognize what we are looking at. The dividing line between the light and dark sides of an object can give a good indication as to how far the object is from the light. The more shadow there is, the closer the light source is, as shown in Figure 7.4.
Likewise, the less shadow there is, the farther away the light source is, as shown in Figure 7.5.
Cast shadows tend to be very crisp and sharp when close to the object, gradually softening as they stretch out, as shown in Figure 7.6.
The size and shape of the shadow depends on a number of conditions, including the size and distance of the light source. For this reason, cast shadows are generally not the best indicators of form, but they can be very useful in giving clues as to an object's surroundings. For example, one clue they provide is how far from another object, or background, the object casting the shadow is located. Look at Figure 7.7 and you can quite obviously tell which sphere is closer to the wall and even which sphere is larger.
Cast shadows can also give you important clues about where an object is in the environment and in relationship to the viewer. In Figure 7.8, the shadow cast by the object gives you valuable information as to where the object is in relation to the viewer, even when the object casting the shadow is out of view.
A second use of value is the expressive. Is your work predominantly light or dark? A dark image would be appropriate if you wanted to create moody effects such as danger or sadness. On the other hand, a light image would be more appropriate for images with the opposite types of feelings. Figure 7.9 shows an example of both a predominantly light and a predominantly dark image.
A third use of value is the decorative. Using values decoratively eliminates the need for a light source in a conventional sense. This approach works best with nonrepresentational or decorative art types, as shown in Figure 7.10.