> This solution has the problem you expected. The backgrounds of the pictures are black...
So, what we have to do is really simple. Open the icon, check for the areas with transparent color, change them to the color of Your choice, preferably white ... no, a smooth pink for a girl ... . When we do that, we try not modify the areas that are intended to be black (and should remain black). When we are doing that anyway we can also check for the colordepth and maybe change it to what we like. And finally save it as a new bitmap.
I *really* don's see Your problem there