Color Essay, Research Paper
Color is the curves, where the height of the curve represents the amount, or intensity, of that particular wavelength. Everyone of these distribution curves then corresponds to a color of light. Many of the colors we are familiar with appear on the EMF visible spectrum, such as red and yellow. We would therefore expect the distribution curves of these colors then to have a positive value only at a certain wavelengths. Under most conditions this is not true–there are usually traces of all the other wavelengths in a color. However, if a notable peak in the distribution curve appears, the color of that curve will be a variant on the color corresponding to that peak s wavelength. We call this the dominant wavelength. While the number of different colors and the number of different distribution curves are both infinite, several different distribution curves may be perceived as the same color. For instance, a distribution with a dominant wavelength at yellow and a distribution with peaks at red and green may both be perceived as yellow. We call such sets of distributions metameters. The distribution curve which is a maximum along the entire visible spectrum produces a color which we call pure white. While pure white (or simply white ) light is difficult to attain, it is often used as a reference in color studies. Now back to our billiard ball example: The matter in which the billiard ball emanates light is by reflection. The medium of the ball will reflect a subset of any light that strikes it. It is this reflected light that enters our eye when we look at the ball. Non-luminous media, such as the ceramic of the ball, can only reflect light in the environment; they cannot add any new light. The ball must be reflecting light which has an EMF distribution curve that is perceived as blue. Therefore the original light which struck the ball must have had at least all of those wavelengths in its EMF distribution. In other words, the distribution curve of the original light must encompass or envelop the distribution curve of the reflected light. When white light is the original light, we are guaranteed that this light will contain all of the wavelengths that a medium might reflect. Therefore, white light is used as a reference for determining the color of a medium. Suppose we now subject the billiard ball to white light, Each bit (or ray ) of this light that hits the ball will be partially reflected. Since the distribution of the reflected light corresponds to what we perceive as blue, we can now say the color of the billiard ball is blue. The color of any medium is determined by subjecting that medium to white light and observing the light reflected by that medium. Remember that light is energy and every bit of it must end up somewhere. So what happens to the other parts of the whit light that the ball does not reflect? This light is absorbed by the ball and probably converted into heat energy. Therefore the ball will gradually heat up as long as it is subjected to light that it cannot reflect. (This is why white clothes are cooler in the summer than black clothes.) What happens when the original light is not white? If the color of the original light encompasses the color of the object, then the color of the reflected light will not be affected. Otherwise, the distribution curve of the reflected light will be lessened, and we will perceive that object as a different color. For instance, our blue ball, under blue-green light will still look blue, but under orange-yellow light, will reflect very little light, and we will perceive the ball as being black. Back to distribution curves: Recall that a curve which is a straight horizontal line at the maximum value that corresponds to white light. A straight line at zero corresponds to black. Any curve which is a horizontal straight line will be a shade of gray–these are colors which have equal amounts of all the wavelengths at some intensity. All the other colors have differently-shaped curves. Recall that the dominant wavelength of a curve often describes its color. The amount of that dominant wavelength in relation to other wavelengths is its saturation. These are colors which we perceive as very sharp or hot. Curves that are very high at the dominant wavelength and very low elsewhere are said to be highly saturated. Curves in which the dominant wavelength is not much higher than the rest of the spectrum are said to be very unsaturated. An example of these types of colors would be pastels.
Each color within that triangle is then a possible color by those primaries. We call such a triangle a gamut. Note that due to the shape of the color space, it is clear that no three (or any greater number) of visible primaries create a gamut which defines all the visible colors. Therefore, whenever using a mixing system, same colors will always be lost. We often call the gamut defined by a particular set of primaries as its color space. The defining of a color space by components is called a color model. Red, green, and blue are a popular choice of additive primaries, and are the colors chosen by most computer monitor manufacturers. It can be seen that the red, green, and blue (RGB) space encompasses a substantial portion of the entire color space. Therefore the RGB model is not a bad choice of color models. For example, cyan, yellow, and green would not be a very good choice of color models as its color space does not encompass much of the total color space, and many colors would be lost. The RGB model can be thought of as a cube, where amounts of red increase across, amounts of green increase forward, and amounts of blue increase up. Every color in the RGB space then lies in this cube. Black is at the origin, and white is at the extreme corner. Grays lie on the main diagonal. [RGB cube] What if we want to mix media, for instance paint or ink, rather than light? Using media for color mixing results in subtractive mixing. The media can only reflect light, therefore combining two media results in a medium which can only reflect those wavelengths that both of the original media could reflect. The resulting color distribution curve will be the intersection of the two original curves. A popular choice of subtractive primaries would naturally be the inverses of red, green, and blue. These are cyan, magnetta, and yellow, respectively. By using these primaries we obtain the same gamut as we had with the RGB model. Subtractive mixing is a complicated process which depends heavily on the transparency and purity of its media. Mixing cyan, magnetta, and yellow should produce black, so many printing devices use black to mix in order to save on the three colors. This is often referred to as a CMYK printing device. The color model used by NTSC broadcasting is called YIQ. The components of this model are the same Y as in the CIE model. The Y component is basically they brightness and is the only component used by black-and-white TV sets. The I and the Q components carry the chromatic information. The gamut defined by this model is a subset of the RGB space, meaning that not as many colors are available via YIQ as are in RGB. Another way to think of colors is by their hue, saturation, and births. By quantifying these characteristics, we can construct a color model which has the same color space as RGB, but is more intuitive to use. What we get is the HSV hexacone (the V is for value which is essentially brightness.) Black lies at the apex of this cone, and white lies at the corner of its base. All the fully-saturated colors lie on its outside surface, and all its brightest colors lie on its base. The grays lie on the center axis, and how far a color lies from the axis defines its saturation. Some find this model easier to use because you can start with the hue you want and then adjust the saturation and brightness. Some ways in which we verbally describe variations in color are by hues, saturation, brightness, tones, shades, and tints. A shade is a variation of a color which makes it less light; i.e.brings it closer to black. A tint decreases saturation and brings a color closer to white. A tone brings a color closer to gray. In the HSV model, tints correspond to moving toward the base; shades move towards the apex, and tones move towards the central axis.