It is said that people and digital cameras have color sense only for red, green and blue. So when we see violet/purple in a rainbow, whether with our eyes or in a photo, we should be seeing a color mixture dominated by red and blue, with less green.
Is this correct and if so, where is the red coming from?
And do rainbows have violet for the same reason black lights are violet?
Note: yes, there are similar questions such as this one but I don't think anyone has asked this question directly.