The grey used as background is not the Amstrad CPC's grey... which is actually "inside" the cube (not displayed).
*How to extend the cube
With a certain limit and providing the use of fine regular dithering, the RGB cube of the Amstrad CPC can be stretched into bigger RGB cubes.
Such cubes are also a guide to get the smooth gradiants from one CPC colours into another.
[[File:R2G2B2 EGA palette on CPC.png]]
This is the CPC palette stretched into a R2G2B2 cube (bits, not values) with help from dithering, hence giving 4x4x4= 64 colours.
[[File:R5G5B5 CPC complete ditherings.png]]
This is the CPC palette stretched into a R5G5B5 cube (values, not bits) with help from dithering, hence giving 5x5x5 = 125 colours.
Notice how some colours can be obtained with up to 4 different combinaisons, yet with the same result. But when considering on screen pixels reactions, notably during flickering technics, some combinaison may be better than others in order to reduce the flash effect of the flickerings.
Bigger RGB cubes would need the use of unpractical ditherings (other than 50%) and perhaps mix of more than 2 colours. This would simply not work properly.
==='''12-bit RGB of the PLUS'''===