rgb -> hsv and back

[Georg Leugner <piece gmx net>]

Hallo,

I'm currently coding on the one click contrast filter like picassa has.
But I need some information:
1. First and most important. Is there somewhere hidden more
documentation than on the get involved page?
2. I need to convert a RGB pixbuf to HSV. I couldn't find a method which
does that, but i found some methods using hue, saturation... Do I miss
something?

Kind regards,

georg