this image is pretty helpful. With light you’re starting with white (the center of the left diagram) and subtracting colours to get your ideal colour. With ink, you’re adding colour to get your ideal colour, and adding all of your colours will get you to black.
Your intuition is on the right track, but it works “the other way around”.
RGB are additive primary colours, because the colour you see when you look at something that emits light is the actual colour of the light. And so when you mix two coloured lights, the colours add up (additive colours). And adding every colour gives you white.
CMY are instead subtractive colour, because when you look at something that does not emit light, the colour you see is just the light that bounces off of it, while some colours get absorbed. So when you mix paints, the resulting paint absorbs more colours, and you only see what’s left, so the colours subtract down (subtractive colours). And subtracting everything gives you black.
P.s. mathematically, any three independent colours could be used as primary. Independent means that you can’t get any of the three by mixing the other two (i.e. blue, red, and purple are not independent). But those two triplets are the most obvious choices.
You might recall that as a kid, they taught you that primary colours were Red, Blue and Yellow instead of CMY, and yet mixing worked fine.
Right, CMY for ink, RGB for light though.
this image is pretty helpful. With light you’re starting with white (the center of the left diagram) and subtracting colours to get your ideal colour. With ink, you’re adding colour to get your ideal colour, and adding all of your colours will get you to black.
Your intuition is on the right track, but it works “the other way around”.
RGB are additive primary colours, because the colour you see when you look at something that emits light is the actual colour of the light. And so when you mix two coloured lights, the colours add up (additive colours). And adding every colour gives you white.
CMY are instead subtractive colour, because when you look at something that does not emit light, the colour you see is just the light that bounces off of it, while some colours get absorbed. So when you mix paints, the resulting paint absorbs more colours, and you only see what’s left, so the colours subtract down (subtractive colours). And subtracting everything gives you black.
P.s. mathematically, any three independent colours could be used as primary. Independent means that you can’t get any of the three by mixing the other two (i.e. blue, red, and purple are not independent). But those two triplets are the most obvious choices. You might recall that as a kid, they taught you that primary colours were Red, Blue and Yellow instead of CMY, and yet mixing worked fine.
Oops, you’re right! That’s what I meant to say but I got mixed up