How are there more colours than we can see?

Question

For example, [this colour wheel has 12 sections](https://www.spectrumnoir.com/wp-content/uploads/2017/04/Colour-Wheel-2.jpg) and performs a full ‘loop’ for lack of a better term (i.e. starts at red, traverses to the polar opposite, and returns the natural way). We can see every one of these clearly, and every colour in between those two colours as it’s simple a mixture, or a mixture of a mixture, or so on. So how can a colour exist outside this wheel?

In: Biology

Answer 1

That wheel only shows a single variable, hue, as a function of angle. Depending on which colour model you want to use, it needs three coordinates, Red, Green & Blue or Hue, Lightness & Saturation. Where on that ring is brown? or grey? or sky blue? Your colour ring is too simplistic.