Color

Color is a very important property in the visual interface. Because color has attractive qualities, use it to identify elements in the interface to which you want to draw the user's attention — for example, the current selection. Color also has an associative aspect; we often assume there is a relationship between items of the same color. Color also carries with it emotional or psychological qualities. For example, colors are often categorized as cool or warm.

When used indiscriminately, color can have a negative or distracting effect. It can affect not only the user's reaction to your software but also productivity, by making it difficult to focus on a task.

In addition, there are a few more things to consider about using color:

• Although you can use color to show relatedness or grouping, associating a color with a particular meaning is not always obvious or easily learned.
• Color is a very subjective property. Everyone has different tastes in color. What is pleasing to you may be distasteful to someone else.
• Some percentage of your users may work with equipment that only supports monochrome presentation.
• Interpretation of color can vary by culture. Even within a single culture, individual associations with color can differ.
• Some percentage of the population may have color-identification problems. For example, about 9 percent of the adult male population have some form of color confusion.

The following sections summarize guidelines for using color: color as a secondary form of information, use of a limited set of colors, allowing the option to change colors.

Color as a Secondary Form of Information

Use color as an additive, redundant, or enhanced form of information. Avoid relying on color as the only means of expressing a particular value or function. Shape, pattern, location, and text labels are other ways to distinguish information. It is also a good practice to design visuals in black and white or monochrome first, then add color.

Use of a Limited Set of Colors

Although the human eye can distinguish millions of different colors, using too many usually results in visual clutter and can make it difficult for the user to discern the purpose of the color information. The colors you use should fit their purpose. Muted, subtle, complementary colors are usually better than bright, highly saturated ones, unless you are really looking for a carnival-like appearance where bright colors compete for the user's attention.

Color also affects color. Adjacent or background colors affect the perceived brightness or shade of a particular color. A neutral color (for example, light gray) is often the best background color. Opposite colors, such as red and green, can make it difficult for the eye to focus. Dark colors tend to recede in the visual space, light colors come forward.

Options to Change Colors

Because color is a subjective, personal preference, allow the user to change colors where possible. For interface elements, Windows provides standard system interfaces and color schemes. If you base your software on these system properties, you can avoid including additional controls, plus your visual elements are more likely to coordinate effectively when the user changes system colors. This is particularly important if you are designing your own controls or screen elements to match the style reflected in the system.

When providing your own interface for changing colors, consider the complexity of the task and skill of the user. It may be more helpful if you provide palettes, or limited sets of colors, that work well together rather than providing the entire spectrum. You can always supplement the palette with an interface that allows the user to add or change a color in the palette.