Color Basics Part 2 – What is Color?
Light is essential for vision. Light causes color. Without light, color would not exist. Light that appears white to us, such as light from the sun, is actually composed of many colors. Each color has its own measurable wavelength or combination of wavelengths. (Light travels in waves, much like water in a pond when you drop a stone in it, except light waves are extremely small.) The wavelengths of light are not colored, but produce the sensation of color in our brains.
Light is a form of energy. All wavelengths of light are part of the electromagnetic energy spectrum, which is a continuous sequence of energy waves that vary in length from very short to very long.
Visible Light – the wavelengths our eyes can detect – is a very small portion of the entire spectrum. If the entire spectrum of energy waves were to be represented by a straight line scale (Short waves at one end and long waves at the other) that measured 10 feet long, the amount of energy waves that we can see as visible would be just a fraction of an inch in the middle of that scale. The visible portion of energy waves is miniscule compared to the whole. To the left of the visible portion of the spectrum, we would find shorter, non-visible waves of energy that would be classified as ultra-violet, then X-rays, and at the extreme end with the shortest energy waves, Gamma rays. On the other side of visible light, as waves get longer, and again non-visible, include infra-red, microwaves, and at the extreme, radio waves.
If we look more closely at just the visible portion of the spectrum, we would see at the short wave end, energy we perceive as blue. At the other end, where the waves are longer is the energy we perceive as red. All the other colors we can see in nature with our eyes are found somewhere along the spectrum between blue and red. If we look at the visible light in order of wavelength, the colors would lay out as follows:
Deep blue merges to lighter blue, or cyan.
Cyan merges to green.
Green merges to yellow.
Yellow merges to Red.
Red merges to purplish red, or magenta.
No where in this visible area includes a color of white light as a single color. As we will discover, white light is the combination of all colors of light shown together. We can separate a beam of white light into all the colors by passing it through a glass prism that causes the light beam to refract at slightly different angles, thus separating the white light into all the colors. When the sun comes out after a rain storm, water droplets in the air can act as prisms and display the arc of colors in the sky we see as a rainbow.
If the visible portion of the spectrum is divided into thirds, the predominant colors are red, green, and blue. These are the primary colors of light. (also referred to as RGB) We can arrange these primary light colors in a circle, commonly known as the color wheel. Imagine the wheel as a clock face, and place the color red at 12:00. Place Green at 8:00 and Blue at 4:00. In between the primary colors are the secondary colors of cyan, magenta and yellow light, which form another triangle. Place cyan at 6:00, magenta at 2:00 and yellow at 10:00. These, of course, represent pure colors. Millions of colors can be created by mixing different intensities of each primary color in different combinations. The more colors that are mixed, the lighter the color becomes, until it becomes white when all colors are mixed with full intensity. Likewise, when colors are mixed with low intensity, the color approaches black. Where there is an absence of light you cannot see color.
Your television or computer monitor creates color using the primary colors of light. The monitor screen starts out as black and creates color when electrons are generated that strike a mosaic of thousands of red, green and blue phosphors within the monitor’s screen. When all the red, green and blue phosphors are illuminated simultaneously, the black screen becomes white. Adding equal amounts of red, green and blue light creates white light. This is called the ADDITIVE COLOR principle.