Page 19 - DCAP504_Computer Graphics

Computer Graphics

Color models are of two types, as depicted in the figure 2.1.

Figure 2.1: Color Models

1. Additive Color Models: Additive color models are those color models, which use light for
displaying colors. In these color models, colors are seen as an aftereffect of transmitted light.

The RGB color model is an example of an additive color model.

2. Subtractive Color Models: Subtractive color models are those color models, which use printing
inks for displaying colors. In these color models, colors are seen as an aftereffect of reflected light.

The CMYK color model is an example of a subtractive color model.

2.1.1 RGB Color Model
The RGB color model is an additive color model, which uses three primary colors, namely, red (R),
green (G), and blue (B). These primary colors can further be used to create secondary colors, such as
yellow, white, and magenta. Computers can display approximately 16.7 million colors using this color
model.
In RGB model, every color’s measurement is done with a value that ranges from 0 to 255, where 0
means no light, and value 255 means maximum intensity. This (0 to 255) is the limit of storing
information in 1 byte of computer memory. In RGB model, 3 bytes (24 bits) of information are needed
for defining the three primary colors RGB.

A large percentage of the visible band of colors can be represented by mixing red, green, and blue
(RGB) colored light in various intensities and proportions.
RGB colors are also called as additive colors, as they combine to create white color. In other words,
adding all colors creates white, that is, all visible wavelengths are transmitted back to the eye. Additive
colors are used for monitors, video, and lighting.

Did you know? Your computer or television monitor, creates color by emitting light through red,
green, and blue phosphors.

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