You could argue that art is the interpretation not the media, all paintings are essential just paints applied to a canvas. I think the computer mind is to logical to contemplate an illogical idea and rationalize it. I also think that computers would require emotion, maybe even soul before true creativity is accomplished. Any animal can move around paint on a canvas, not sure about a GOD but certainly nature has a huge effect, geometry is perhaps a possibility for computers to make a transition into art.
Another interesting thought is that idea that monkeys would eventually write a Shakespeare play given enough time pressing buttons at random, the same applies for pixels, inks and so on.
Another interesting aspect of art creation (and I'm going to be making assumptions based on my own talents in artistry,) is that art can be highly logical and very literal. For example, realism: to accomplish realism, you must draw/paint in a very specific way which lines up with how we view objects in the world. It requires a lot of technical ability, and you can get away with it without any creativity whatsoever (otherwise, we could make the assumption that every photograph is a piece of art, including the photographs of me speeding past a red light once being used against me in court.) To create a perfect reproduction of life through a pencil requires only technical ability; computers do this already, and much more efficiently.
Taking into consideration the idea of monkeys and Shakespeare, can we then define art with the requirement of creative input? Though a set of monkeys could eventually pound out Shakespeare, because they do not understand what they're doing, we cannot assume they understand a thing they're writing about, outside of being a random assortment of key presses. Thus, although the two copies of Shakespeare, one written by the man, and the other written by monkeys, are identical copies, we can assume one is art and the other isn't.
At what point in time would a computer be able to create art, then? When it has motivation? At which point, it would need to have a reason to create, not because it is programmed to, but because it wanted to. It would have to first experience pain. We would have to reverse-engineer the human being. Considering that our entire lives are interpreted through a series of electrical impulses in our minds, it could be possible, if we recreate the human mind with resources outside the normal flesh and blood, to invent an artist. I imagine it would be incredibly difficult, but I tend to believe nothing's impossible.
If you ask me, that will be the final Turing test. When an A.I. creates an original composition that I recognize as "art," I'll call it a person.
Imagine if you could purchase an artificial family member and never tell the difference. Anyway, in relation to the thread, I believe there's an odd connection between an artificial person and a real one; in one aspect, you know they're machine, but in another, you know they feel.