private static double convertHueToRgb(final double v1, final double v2, double vH) {
        if (vH < 0) {
            vH += 1;
        }
        if (vH > 1) {
            vH -= 1;
        }
        if (6 * vH < 1) {
            return v1 + (v2 - v1) * 6 * vH;
        }
        if (2 * vH < 1) {
            return v2;
        }
        if (3 * vH < 2) {
            return v1 + (v2 - v1) * (2 / 3.0 - vH) * 6;
        }
        return v1;
    }
DIN99o.

@param l99o lightness of color.
@param a99o position between red and green.
@param b99o position between yellow and blue.
@return DIN99o colors converted to CIELab color space.
@see <a href=
     "https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum">https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum</a>
src/main/java/org/apache/commons/imaging/color/ColorConversions.java