Color theory — two mixing models.

• Additive primaries: Red, Green, Blue (RGB). Used by light-emitting displays — monitors, projectors, sensors. R + G + B = White.

• Subtractive primaries: Cyan, Magenta, Yellow (CMY). Used by inks and dyes — printing, color photography. C + M + Y = Black (in theory).

• Displaying a digital image uses additive mixing (RGB).
• Color photography (film prints) uses subtractive mixing of complementary dyes.