Colours, colours, colours...

Painting is my hobby and so colours have always attracted me. And so this blog....

Today on our coffee table we were having discussions about the spinning of a coin(where my friends were trying all possible ways to spin a poor 5 rupee coin).I dont remember when this discussion shifted to the spinning of a wheel with colours(Since we are experts in making sense out of non-sense and non-sense out of sense.. So it doesnt matter anyways :-) )
Our interest shifted from the colours of a rainbow to primary colours in no time (the colour of our sandwich aunty's saree brought light to the difference between indigo and violet ;-) ) and I was wondering why we have different theory for primary colours.

Being a software engineer, R(red)G(green)B(blue) are the three primary colours that I can think of. But ever wondered then, why our physics books talked about red, blue and yellow as the primary colours.

Well, lets explore...

Upon surfing through the net, I found that there are two types of primary colours, additive and subtractive. Doesnt make sense? Neither to me.. Lets explore more...
(courtesy: http://www.colourtherapyhealing.com/colour/primary_colours.php)
Additive primary colours are used when we are dealing with mixing emitted light. The additive primary colours are red, green and blue. All colours (well not really all) can be produced by mixing these three colours. An example of their use is on a computer monitor, where varying intensities of red, green and blue light are used to create the colours we see. If full intensity red, green, and blue are mixed we get white light.
Subtractive primary colours are used when we are dealing with reflected light. Because of this we use them when we are mixing paints or inks. The subtractive primary colours are cyan, magenta and yellow. A printer, for example, mixes these three colours to produce different colours on the paper. If we mix full intensity cyan, magenta and yellow, we get black.

NOW THE CONFUSION:

The confusion normally arises early in school when we are very young and are using paint or crayons. If we need to create a colour that we do not have, then of course we should mix the right proportions of the subtractive primary colours - cyan, magenta and yellow. However, it is very rare that we will find cyan or magenta paint or crayons amongst the selection given to a young child(thats true :-( ), so our teacher helpfully advises us to use red as an approximation to magenta, and blue as an approximation to cyan. And that's it, from that moment on we believe that we can mix red, yellow, and blue to make any colour, and that they therefore must be primary colours.

Just to add a bit of confusion to the terminology, the secondary colours of emitted light are the primary colours of reflected light. This can often confuse people into thinking that CMY are just secondaries, when in fact they are primaries.

Hmm... gotcha!!! :-)
So if I spin my friend in front of the wheel with the three primary colours, what color does he see?????
Black, irrespective of the type of primary colour ;-);-) [Donno whether he'll see stars as well.. We didnt discuss this :-( , maybe tomorrow ;-)]