HSY色空間変換

gistfile1.java

/*
http://sourceforge.jp/projects/hsy-color/wiki/HSY%E8%89%B2%E7%A9%BA%E9%96%93%E3%81%AB%E3%81%A4%E3%81%84%E3%81%A6
*/

private int RGBtoHSYtoRGB(int rgb) {
	float h;
	float y;
	float s;
	float S;
    float MAX;
    float MIN;
    float MID;
//    float pmax;
    float pmin;
    float pmid;
    float f;
	float r = (float) Color.red(rgb)   / 255;
	float g = (float) Color.green(rgb) / 255;
	float b = (float) Color.blue(rgb)  / 255;
	float max = Math.max(Math.max(r, g), b);
	float min = Math.min(Math.min(r, g), b);
	float cr;
	float cg;
	float cb;
	final float pr = 0.298912F;
	final float pg = 0.586611F;
	final float pb = 0.114478F;
	
	//RGBからHSY
	y = pr * r + pg * g + pb * b;
	if (max == min){
		h = 0;
		s = 0;
	} else {
		s = (max - min) / max;
		cr = (max - r) / (max - min);
		cg = (max - g) / (max - min);
		cb = (max - b) / (max - min);
		h = r == max ? cb - cg : g == max ? 2 + cr - cb : 4 + cg - cr;
		h = h * 60;
		h += h < 0 ? 360 : 0;
	}

	y = 1F;
	//HSVからRGB
	int cond = (int) Math.floor((double) h / 60);
	f = (h % 60F) / 60F;
	switch(cond){
	case 0:
//		pmax = pr;
		pmid = pg;
		pmin = pb;
		S = (1 - y)/(pmid - pmid*f + pmin);
		S = S > 1 ? 1 : S;
		MAX = y / (1 + S*((f - 1)*pmid - pmin));
		MID = (1 - s + s*f)*MAX;
		MIN = (1 - s)*MAX;
		r = MAX;
		g = MID;
		b = MIN;
		break;
	case 1:
//		pmax = pg;
		pmid = pr;
		pmin = pb;
		S = (1 - y)/(pmid - pmid*(1 - f) + pmin);
		S = S > 1 ? 1 : S;
		MAX = y / (1 + S*(((1 - f) - 1)*pmid - pmin));
		MID = (1 - s + s*(1 - f))*MAX;
		MIN = (1 - s)*MAX;
		g = MAX;
		r = MID;
		b = MIN;
		break;
	case 2:
//		pmax = pg;
		pmid = pb;
		pmin = pr;
		S = (1 - y)/(pmid - pmid*f + pmin);
		S = S > 1 ? 1 : S;
		MAX = y / (1 + S*((f - 1)*pmid - pmin));
		MID = (1 - s + s*f)*MAX;
		MIN = (1 - s)*MAX;
		g = MAX;
		b = MID;
		r = MIN;
		break;
	case 3:
//		pmax = pb;
		pmid = pg;
		pmin = pr;
		S = (1 - y)/(pmid - pmid*(1 - f) + pmin);
		S = S > 1 ? 1 : S;
		MAX = y / (1 + S*(((1 - f) - 1)*pmid - pmin));
		MID = (1 - s + s*(1 - f))*MAX;
		// (1-f)*MAX
		MIN = (1 - s)*MAX;
		b = MAX;
		g = MID;
		r = MIN;
		break;
	case 4:
//		pmax = pb;
		pmid = pr;
		pmin = pg;
		S = (1 - y)/(pmid - pmid*f + pmin);
		S = S > 1 ? 1 : S;
		MAX = y / (1 + S*((f - 1)*pmid - pmin));
		MID = (1 - s + s*f)*MAX;
		MIN = (1 - s)*MAX;
		b = MAX;
		r = MID;
		g = MIN;
		break;
	case 5:
//		pmax = pr;
		pmid = pb;
		pmin = pg;
		S = (1 - y)/(pmid - pmid*(1 - f) + pmin);
		S = S > 1 ? 1 : S;
		MAX = y / (1 + S*(((1 - f) - 1)*pmid - pmin));
		MID = (1 - s + s*(1 - f))*MAX;
		MIN = (1 - s)*MAX;
		r = MAX;
		b = MID;
		g = MIN;
		break;
	}
	int R = (int)(r*255);
	int G = (int)(g*255);
	int B = (int)(b*255);
	return Color.rgb(R, G, B);
}