NAME
        ConvertRGBToHSB -- convert from an RGB color space to an HSB color
                           space. (V39)
   SYNOPSIS
        ConvertRGBToHSB(rgb, hsb);
                        A0   A1
        VOID ConvertRGBToHSB(struct colorwheelrgb *, struct colorwheelhsb *);
   FUNCTION
        Converts a color from an RGB representation to an HSB representation.
   INPUTS
        rgb - filled-in colorwheelrgb structure containing the values to
              convert
        hsb - structure to receive the converted values
   BUGS
        Even though all communication with the color wheel is done using full
        32-bit color components, color calculations are currently done using
        16-bit math, which can cause certain rounding errors to appear.