Retrieves the hue value in degrees from a packed (A)RGB color. Adapted from a C algorithm by Eugene Vishnevsky. http://www.cs.rit.edu/~ncs/color/t_convert.html

HueFromRgb.java

public class HueFromRgb {
    // Retrieves the hue value in degrees from a packed (A)RGB color.
    // Adapted from a C algorithm by Eugene Vishnevsky.
    // http://www.cs.rit.edu/~ncs/color/t_convert.html
    public static float hueFromRgb(int rgb) {
        int r = (rgb >> 16) & 0xFF;
        int g = (rgb >> 8) & 0xFF;
        int b = rgb & 0xFF;

        float min = Math.min(Math.min(r, g), b);
        float max = Math.max(Math.max(r, g), b);
        float delta = max - min;

        if(max == 0x00 || min == 0xFF) {
            // Black or white
            return 0;
        }

        float h;

        if(r == max) {
            // Between yellow and magenta
            h = (g - b) / delta;
        } else if(g == max) {
            // Between cyan and yellow
            h = 2 + (b - r) / delta;
        } else {
            // Between magenta and cyan
            h = 4 + (r - g) / delta;
        }

        // Degrees
        h *= 60;
        if(h < 0) {
            h += 360;
        }

        return h;
    }
}