to phrase the question differently, how do the electrical signals in our brain produce the full-color mental images
and to rephrase the question, how do the electrical signals in electronic devices produce the full-color visual images?
We know that this answer is out there, and some clever people can explain its technology. We know its whole 150 years of history and we know how it has been evolved through generations, and how does it work in transistor level.
Current knowledge of DNA does not allow us to get the absolute working mechanism of a living thing, we've just started to isolate the individual genes and make artificial copies of them. We are kind of harvesting the nature in DNA level, just as our ancestors had harvested the soil to get what they needed from nature.
Many of us -apart from blind people- born and live with functional onboard cameras and hard disc memory capacity. When you get older, both will betray you. Currently, we might not be able to replicate what nature can do as a living organism, although at least we know the logic, limits and major roles of the components. We can predict that it's not an "essence" going inside of our brains, but it is a repeatable technology. Set of representations and interpretations: Cable carries electricity, but this electricity was already sent by a sensor in certain frequency and voltage, so a different electronic switches start to interpret light, colour, depth and produce a photography.
Nature does the similar thing, although it uses organic material instead of slicon. It may be doing it in a more sophisticated fashion than our non-replicating digital gadgets -and their 0-1 logic-; but it is a fact that it can not produce a material copy of the image. When we exactly grasp the technology behind the brain, we would be able to see the imagination board of our brains, we would download it, share it, motion picture it, print it; and other way around journey as well: We could send images and other information to brain's mental board.
Only if we could crack the system information code... Until then, what we know in this area is simply "limited".