RGBA

From DmWiki

Shorthand notation for available Pixel components. RGBA stands for 'Red, Green, Blue, Alpha'. When no alpha value is required, people often use RGB ('Red, Green, Blue').

Using the colours Red, Green and Blue computer systems can re-create all displayable colours. Since visual displays work by emitting light to the viewer, by increasing the red, green and blue components of a pixel one can create a colour closer to white (white light is really just a mixture of the entire spectrum. This is why rainbows form when sunlight is refracted by droplets of water). This is an additive system, whereas in the real world paints and such work on a subtractive system since each colour limits what colours of light are reflected back to the viewer.

The alpha value determines how transparent the material is. In normal operation, a value of 1.0 indicates the surface is completely solid and at 0.0 it will not be seen. However in the context of 3D graphics, the developer is free to use the alpha value for any number of complex operations upon the source and destination pixels to create a desired effect.