Tattoo cover up, is it possible?

I have a fairly large tattoo on my right leg/upper thy. It is of a gypsy and the shading on her hair is very dark and most parts it's black shading very heavily. I want to cover it with some japanese flower/artwork to start a sleeve (well... pant leg I suppose). The gypsy is too random to work into any sleevework and I just plain dont like it. Any suggestions, I have a picture if you want to see it.