"RGB", stands for Red, Green, Blue one of the most popular color models. A spectrum of colors are created by mixing red green and blue light as seen in the simplified color model on the left. Notice that mixing red light and green light creates yellow light. It is important to remember that color light and color pigments are very different. The traditional color wheel for artists uses red, blue, and yellow pigment to create many colors. Mixing all colors results in a grey/brown pigment. However, light acts very differently. Just as a prism can divide white light into many colors, adding colored light produces white light as seen in the center of the model. Because of this RGB is referred to as an
additive model because the light beams are added together.
History
The RGB model is, "is based on the Young–Helmholtz theory of trichromatic color vision, developed by Thomas Young and Hermann Helmholtz, in the early to mid nineteenth century, and on James Clerk Maxwell's color triangle that elaborated that theory (circa 1860)."Trichromacy occurs when animals possess three color receptacles within the eye. Humans and primates are trichromats
and therefore respond well to color models based on tri-color sources. The image on the left shows the large variety of colors possible in this model.
Digital
Digitally each color is indicated by three bytes representing three numbers from 0-255. Each number is associated with a color intensity. Therefore the color [255,0,0] would be pure red, with red light emitted at the highest intensity and no green or blue light. Likewise one could guess that the color [255,255,255] is white, and (assuming a black monitor screen) the color [0,0,0] is black. Therefore the entire grey spectrum can be represented by three equal numbers, such as [126,126,126]. The color cube shows 3 dimensionally how changing these parameters results in a wider range of colors than shown in the 2 dimensional color wheels.
While the model is based on emitted light software converts and prints color images with no need for user input. Users should be aware that other models exist such as C,M,Y,K standing for Cyan, Magenta, Yellow, and Black. Converting between models may result in slightly altered color characteristics.
When using image editing software like photoshop it is possible to closely control the RGB values of each color and to save that assignment as a "
swatch". This helps ensure color consistency which often cannot be detected by the human eye on a monitor but are apparent in print.
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