RGB和HSV 之间的转换

public static float[] rgb2hsb(int rgbR, int rgbG, int rgbB) {
    assert 0 <= rgbR && rgbR <= 255;
    assert 0 <= rgbG && rgbG <= 255;
    assert 0 <= rgbB && rgbB <= 255;
    int[] rgb = new int[] { rgbR, rgbG, rgbB };
    Arrays.sort(rgb);
    int max = rgb[2];
    int min = rgb[0];

    float hsbB = max / 255.0f;
    float hsbS = max == 0 ? 0 : (max - min) / (float) max;

    float hsbH = 0;
    if (max == rgbR && rgbG >= rgbB) {
        hsbH = (rgbG - rgbB) * 60f / (max - min) + 0;
    } else if (max == rgbR && rgbG < rgbB) {
        hsbH = (rgbG - rgbB) * 60f / (max - min) + 360;
    } else if (max == rgbG) {
        hsbH = (rgbB - rgbR) * 60f / (max - min) + 120;
    } else if (max == rgbB) {
        hsbH = (rgbR - rgbG) * 60f / (max - min) + 240;
    }

    return new float[] { hsbH, hsbS, hsbB };
}

public static int[] hsb2rgb(float h, float s, float v) {
    assert Float.compare(h, 0.0f) >= 0 && Float.compare(h, 360.0f) <= 0;
    assert Float.compare(s, 0.0f) >= 0 && Float.compare(s, 1.0f) <= 0;
    assert Float.compare(v, 0.0f) >= 0 && Float.compare(v, 1.0f) <= 0;

    float r = 0, g = 0, b = 0;
    int i = (int) ((h / 60) % 6);
    float f = (h / 60) - i;
    float p = v * (1 - s);
    float q = v * (1 - f * s);
    float t = v * (1 - (1 - f) * s);
    switch (i) {
        case 0:
            r = v;
            g = t;
            b = p;
            break;
        case 1:
            r = q;
            g = v;
            b = p;
            break;
        case 2:
            r = p;
            g = v;
            b = t;
            break;
        case 3:
            r = p;
            g = q;
            b = v;
            break;
        case 4:
            r = t;
            g = p;
            b = v;
            break;
        case 5:
            r = v;
            g = p;
            b = q;
            break;
        default:
            break;
    }
    return new int[] { (int) (r * 255.0), (int) (g * 255.0),
            (int) (b * 255.0) };
}