Light and Color

The name of the three ways light interacts with matter is Transparent, Translucent, and Opaque. Transparent describes matter that allows light to pass through with little interference. Translucent decribes matter that transmit light but that does not transmit and image. Opaque decribes an object that does not transparent or translucent. We tend to think of objects as having fixed colors—an apple, for example, is red. In reality, an object’s appearance results from the way it reflects the particular light that is falling on it. Under white light, the apple appears red because it tends to reflect light in the red portion of the spectrum and absorb light of other wavelengths. If a filter is used to remove red from the light source, the apple reflects very little light and appears black.
 The fact that the color makeup of light can change, means that shifts can occur in the color appearance of objects illuminated by it. Within limits, the brain compensates for these changes in color appearance and we see things as we expect them to appear. But the changes are there nonetheless and can affect the way people respond to objects and environments. There is a great variety in the color makeup of light that appears white. Direct sunlight at noontime is an almost perfectly balanced light source—it contains all colors in nearly equal quantities. But daylight does experience color shifts.
The color appearance of objects changes dramatically in early morning or in the shade. Electric light sources can also exhibit variations in color makeup. Incandescent lamps tend to produce more red and yellow light than green and blue, and appear to be “warm” in color. Because of the way incandescent light is produced, little can be done to manipulate its color characteristics. With fluorescent and high intensity discharge lighting, this latest technology makes it possible to manipulate the color makeup of a given light source.Generally speaking, whiter light (comprised of equal amounts of all colors) makes colors appear more natural and vibrant. However, some portions of the spectrum are more important to a light’s color makeup than others. Red, blue and green—the primary colors of light—can be combined to create almost any other color. This suggests that a light source containing balanced quantities of red, blue and green light can provide excellent color appearance even if this light source is deficient in other colors in the spectrum.