Can we imagine colours we can't see?

Humans can't see every colour (ultraviolet for example). Some humans are what we call "colour blind" which really just means they can't see certain colours most of us can. Some other animals can see no colour at all. Others can see colours we can't.

Can we IMAGINE, or maybe even dream, colours our eyes can't see? Is it possible for me to imagine what ultraviolet (or others outside human range) looks like? Can my mind's eye conjure it up, the way it conjures up a bright yellow or rich red, even though I've never seen it?

I can imagine other things I've never seen before, like shapes and patterns. Can I imagine colours I haven't experienced? How about "colour blind" humans, can they imagine/dream the colours they have not yet seen?

When I try to conjure up a "new" colour in my mind, no matter what I do, it always ends up being a colour I've seen before, something from the visible spectrum, a piece of any rainbow I've ever seen. I don't seem to be able to imagine a new colour.

What about colour blind people, can they imagine the colours they haven't seen yet? How about after getting special eyewear that fixes the problem, are they able to visualize the new colours from then on? Will they dream with the new colours from then on? How about if they lose the ability to see those colours again, for example they break their expensive custom eyewear that made it possible. Can they always imagine the colours they were only able to see for a short time? Will their brains eventually forget those colours if they don't actually see them for a while?

How about you... can you imagine a colour you haven't seen before? If not, do you think it's even possible?

DRutter