RGB Color Model

The RGB (Red, Green, Blue) color model is based on the additive color theory, where colors are created by combining different intensities of Red, Green, and Blue light.

RGB is a device-dependent color model: different devices detect or reproduce a given RGB value differently, since the color elements and their response to the individual red, green, and blue levels vary from manufacturer to manufacturer, or even in the same device over time. Thus an RGB value does not define the same color across devices without some kind color management.

However, there is another color model derived from RGB named RGBA color model.

RGBA Color Model

RGBA stands for Red Green Blue Alpha. While it is sometimes described as a Color Space, it is actually a three-channel RGB Color Model supplemented with a fourth alpha channel. Alpha indicates how opaque each pixel is and allows an image to be combined over others using Alpha Compositing, with Transparency and Anti-Aliasing of the edges of opaque regions.