I can't visualize at all when awake, but I have been into lucid dreaming in my past and my dreams were visual and more detailed than real life (no bad lenses for the light to go through, I guess). I can also visualize a little bit when on either edge of sleep. I've been noticing that the occasional images that I see in that state are becoming more colorful and detailed. I'm hoping that means actual phantasia in my future, but that's probably just wishful thinking.

I should add that the only things I've ever been able to see when fully awake that didn't come through my retinas are auras (I went through a "learn to read auras" phase a long time ago) and ghosts. Or at least things that I'm assuming aren't actually real, like images of a friend who died before I knew about it and a woman who watched me watch TV for a few weeks. So this might mean that I'm not a complete aphant, or it might mean (based on this article) that sometimes those brain regions/processes can still align for me occasionally.