Just What is Color?
Color is our brain’s perception of the light that registers on the rod and cone cells of our eyes. The light can either be generated directly as color by a device such as a projector, computer monitor, smart phone screen or a television. Or it can be produced by the selective absorption of certain wavelengths of light and the reflection of others as happens when color pigments are applied to substrate surfaces, such as is done by a printer, and then the resulting image is illuminated by a light source. Interestingly, although everyone learned in school that the three primary colors are Red, Blue, and Yellow, these are not the colors used to produce color in either the modern printing deices or in the production of projected color. If you look closely at a television screen, computer monitor, or more obviously a full color digital display system such as one available from our supplier Daktronics ( see the image below) You will notice that the pixels are created with red, blue, and green light sources. By varying the intensity and proportion of each of these 3 light source colors, a full gamut of colors can be produced from black ( all 3 sources off ) to white (all 3 sources on at 100%).
This is an example of a Pixel, or “picture element” from a Daktronics full color LED sign system. It is comprised of 3 separate LED lamps, although there are expensive, single LED lamps available that internally have the 3 color producing junctions. From any reasonable viewing distance the 3 elements loose their individuality and a color is formed in the viewers mind.
Seen below is a standard , basic RGB model showing the primary combinations of color as produced by the same 3 colored illuminants.
Now something to note: if you will examine the RGB color model, you will notice a couple of interesting things- our old friend yellow appears! Not as a “primary” color as we were taught in elementary school, but it has been produced by the illuminants Red and Green! Also, you will see that there are two other “secondary” colors formed, the colors of Cyan and Magenta. These 3 colors, in the form of pigments along with a pure black pigment is used in the standard 4 color printing process known to everyone who has had to go and buy printer cartridges. We will discuss how printers create almost unlimited color using these four pigments (and 2 “other” colors in our professional wide-format HP 26500 printer) in my next blog article.
