The RGB system refers to a color model for film that is based on red, green and blue. From the basis of these three colors, the model constructs the rest of the colors in the image by mixing two or three of these colors in different proportions.
Although these colors are the basis of the colors in the image, none of these colors is specifically defined. Consequently, the red in one RGB color model may be significantly different than the red in a different system.
The CMYB color model, based on the cyan/magenta/yellow/black scale, is a common alternative to the RGB color system.
The original color model of an image is the platform from which the computer software like Photoshop can then effectively edit the image.
In addition to being central to photographic systems, color models such as RGB are also key to how LCD (liquid crystal display) screens and plasma television screens function.