The primary colours traditionally used by painters are Red, Yellow and Blue. Digital photographers should be aware of the fact that light and digital technology have a different relationship with colour. Transmission primaries are RGB ( red, green and blue). Mixing coloured light produces different results from mixing paint that are not intuitive. for example red and green produce yellow – which is not what the eye espects.
There are two ways of dealing with colour. Technical deals with the process of recording and displaying colour RGB. Perceptual deals with the way we see and feel about colour therefore using red, yellow and blue.
We should think of hue as the essential quality that decides how we name a colour – red, purple, blue etc. Hue can be changed by using coloured filters over the lens, or coloured lights. It can also be altered through the camera settings, including adjusting white-balance. FInally it can be altered in post-processing, particularly when shot in RAW.
When we think of a colour we can think of its saturation as pure, intense, saturated or dull, weak, unsaturated. Different hues show maximum saturation at different levels of brightness. Saturation is less-adjustable at the time of shooting than Hue or Brilliance, however modern camera settings do allow alterations. Again, this can be adjusted in post-processing.
We think of colours in terms of how bright they are. For example very bright, bright, fairly bright, average, slightly dark, dark or very dark. Brightness can be controlled by exposure.