said by Weirdal :

thing is, it's hard to change black to any other color because all the details are lost when taking a picture of somethign black.

said by 35375105 :

You can very well take photos of something black by exposing for it. However everything else will be a little overexposed but that doesn't matter because we are only worried about the black part.

However with a camera phone I doubt it will let you meter for the black part. You need a real camera to do that.