In computer graphics, RGB (Red-Green-Blue) is a standard model for representing color.
It is a system that generates various colors by adding varying intensities of the three primary colors (red, green, and blue). It is widely used in displays, televisions, cameras, image processing, and other fields.
The Core Principles of RGB
Additive Color Mixing: RGB belongs to the additive color model, meaning that other colors are created by adding the three primary colors of light (red, green, and blue). When the three colors are added at maximum intensity, white is obtained; when the intensities are all zero, black is displayed.
Channels and Values:
Each color channel (red, green, and blue) is typically represented by an integer from 0 to 255 (8 bits per channel, for a total of 24-bit color depth).
For example, pure red is represented as (255, 0, 0), white is (255, 255, 255), and black is (0, 0, 0). In higher-precision scenarios, floating-point numbers (e.g., 0.0-1.0) or 16-bit integers (0-65535) may also be used.
RGB Applications
Display Devices:
Monitors and television screens display color by emitting light from the red, green, and blue subpixels of each pixel.
For example, a pixel with an RGB value of (120, 200, 50) indicates that the pixel is a mixture of medium-intensity red, high-intensity green, and low-intensity blue.
Image and Video Processing:
Digital images (e.g., JPEG, PNG) and video frames store color information in RGB format.
Image editing software (e.g., Photoshop) allows users to modify colors by directly adjusting RGB values.
Computer Graphics Rendering:
In 3D rendering, the colors of materials and lighting are often defined in RGB.
For example, a red surface might reflect 100% red light and absorb green and blue light (RGB values of (1.0, 0.0, 0.0)).
RGB Variants and Extensions
RGBA: Adds an alpha (transparency) channel to RGB, used to indicate the degree of transparency (0 = fully transparent, 1 = fully opaque).
For example, semi-transparent red can be represented as (255, 0, 0, 0.5).
Other Color Spaces:
CMYK: A subtractive color model used in printing (cyan, magenta, yellow, black).
HSV/HSL: A color model based on hue, saturation, and brightness that better aligns with human visual perception.
Example: RGB Color Mixing
Yellow = Red + Green → (255, 255, 0)
Cyan = Green + Blue → (0, 255, 255)
Magenta = Red + Blue → (255, 0, 255)
Summary
RGB is the fundamental color model used in computer graphics. Colors are represented and mixed by combining the values of the red, green, and blue channels. Understanding RGB is crucial for image processing, display technology, 3D rendering and other fields. It is also the starting point for learning more complex color models (such as HSV and Lab).