Can a dark blue canvas vert top be dyed black ?

Hey does anybody know if a dark blue top can be dyed black. It is a canvas top. And what product would I use, or should I just take it to a upholstery shop ?
Thanks

I think it could being canvas, but evertyhing I dyed back in the laundromat in high school still has the original "tint" to it. Being on a light colored car would help. Couldnt hurt though as your are going to get a black top anyway if it doesnt work.