V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RGB
       Rot Gruen Blau / Red Green Blue (color system, DTP)


The Free On-line Dictionary of Computing (30 December 2018):

RGB

   Red, Green, Blue.  The three colours of light which can be
   mixed to produce any other colour.  Coloured images are often
   stored as a sequence of RGB triplets or as separate red, green
   and blue overlays though this is not the only possible
   representation (see CMYK and HSV).  These colours
   correspond to the three "guns" in a colour cathode ray tube
   and to the colour receptors in the human eye.

   Often used as a synonym for colour, as in "RGB monitor" as
   opposed to monochrome (black and white).