void grayScale(){
	S_RGBA color;
	int x;
	int y;
	unsigned char gs;

	for(x=0; x<width; x++){
		for(y=0; y<height; y++){
			color = getPixel(x,y);
			gs = ROUND(color.red * 0.299 + color.green * 0.587 + color.blue * 0.114);
			color.red = gs;
			color.blue = gs;
			color.green = gs;
			putPixel(x,y,color);
		}
	}
}