colours

Colour

what are colours? Technically speaking, colours are the way our brain, by use of our eyes, interprets electromagnetic radiation of a wavelenght between 350 and 750 nanometers. The different wavelengths are seen as different colours, as in the spectrum below. You have most likely seen a spectrum like this many times before, so I am not going to say anything more about it. A colour wheel is pretty much just the spectrum twisted around so that the violet and red ends are joined. The colour wheel is particularly useful for showing how the colours relate to each other and how you can create new colours by mixing two or more colours.

There are three colours which are referred to as the primary colours. All other colours can be created by mixing these three colours. The primary colours are red, green and blue.
additive colours
Subtractive colours
Red, green and blue?Some of you might have learned that the primary colours are red, yellow and blue. In saying this you are both right and wrong. In classic colour theory, the primaries are red, yellow and blue. However, since here we deal with colours on a screen, it is more practical to think of red, green and blue as primaries. To explain this further we need to introduce two more terms - additive colour systems and subtractive colour systems. The additative colours system is what computer monitors and TV screens use-- any colour source that emits the light itself. If you look very very closely at your screen, you will see that it is built up of tiny red, green and blue dots. In the additative system, you get white when the three primary colours are present at 100%. The subtractive colour system, on the other hand, is what comes to play in printing, drawing, painting and such. This is when the colour does not emit any light of its own, but refects light from its surroundings. In the subtractive colour system, you get black when all colours are mixed. It is in this system that one of the primary colours is yellow.

The secondary colours are what you get when you mix any two adjacent primary colours. Red and green give yellow, red and blue give you magenta and a mix of green and blue result in a cyan colour.The secondary colours are also the primary colours in the subtractive colour system.The tertiary colours are those which lie in between the primary and secondary colours.

posted by moonlight @ 12:38 AM