RGB to CMYK and back algorithm

Question

I am trying to implement a solution for calculating the conversion between RGB and CMYK and vice versa. Here is what I have so far:

  public static int[] rgbToCmyk(int red, int green, int blue)
    {
        int black = Math.min(Math.min(255 - red, 255 - green), 255 - blue);

        if (black!=255) {
            int cyan    = (255-red-black)/(255-black);
            int magenta = (255-green-black)/(255-black);
            int yellow  = (255-blue-black)/(255-black);
            return new int[] {cyan,magenta,yellow,black};
        } else {
            int cyan = 255 - red;
            int magenta = 255 - green;
            int yellow = 255 - blue;
            return new int[] {cyan,magenta,yellow,black};
        }
    }

    public static int[] cmykToRgb(int cyan, int magenta, int yellow, int black)
    {
        if (black!=255) {
            int R = ((255-cyan) * (255-black)) / 255; 
            int G = ((255-magenta) * (255-black)) / 255; 
            int B = ((255-yellow) * (255-black)) / 255;
            return new int[] {R,G,B};
        } else {
            int R = 255 - cyan;
            int G = 255 - magenta;
            int B = 255 - yellow;
            return new int[] {R,G,B};
        }
    }

Answer 1

public static String makeCMYKString(int color) {
    double red = Color.red(color);
    double green = Color.green(color);
    double blue = Color.blue(color);
    double red1 = red / 255;
    double green1 = green / 255;
    double blue1 = blue / 255;
    double max = (Math.max(Math.max(red1, green1), blue1));
    double K = 1 - max;
    double C = (1 - red1 - K) / (1 - K);
    double M = (1 - green1 - K) / (1 - K);
    double Y = (1 - blue1 - K) / (1 - K);
    double CMYK[] = {C, M, Y, K};
    String cmyk = "CMYK = (" + Math.round(C * 100) + " , " + Math.round(M * 100) + " , " + Math.round(Y * 100) + " , " + Math.round(K * 100) + ")";
    return cmyk;
}