OpenCV（三）——PhotoShop中的饱和度调节

PhotoShop的饱和度调节公式：

 ①计算每个像素点三基色最小值和最大值

②delta为两值之差 / 255，如果两值之差为0则不做操作

value为两值之和 / 255

③有RGB图像空间转化成HSL（H色调，S饱和度，L亮度）

L = value / 2

如果L < 0.5 则 S = delta / value;

否则   S = delta / (2 - value);

④Increment / 100 为饱和度

正值为提升饱和度，负值为降低饱和度。

根据不同公式得到新的rgb值。

 

#include 
using namespace cv;
using namespace std;

#define max2(a, b) ( (a) > (b) ) ?  (a) : (b)
#define max3(a,b,c) ( ( (a) > (b) ) ?  max2( a, c) : max2( b, c ) )

#define min2(a, b)  ( (a) < (b) ) ?  (a) : (b)
#define min3(a,b,c) ( ( (a) < (b) ) ?  min2( a, c ) : min2( b, c ) )

const int max_Increment = 200;
int Increment_value;
Mat image;
Mat src;

void on_Trackbar(int , void*)
{
	float Increment= (Increment_value - 100)* 1.0/max_Increment;
	image = src.clone();
	for(int i = 0; i < image.cols; ++i)
	{
		for(int j = 0; j < image.rows; ++j)
		{
			uchar b = image.at(j, i).val[0];
			uchar g = image.at(j, i).val[1];
			uchar r = image.at(j, i).val[2];
			float max = max3(r,g,b);
			float min = min3(r,g,b);
			float delta, value;
			uchar R_new, G_new, B_new;
			float L, S, alpha;
			delta = (max - min) / 255;
			if(delta == 0)
				continue;
			value = (max + min) / 255;
			L = value / 2;
			if(L < 0.5)
				S = delta / value;
			else
				S = delta / (2 - value);
			if(Increment >= 0)
			{
				if((Increment + S) >= 1)
					alpha = S;
				else
					alpha = 1 - Increment;
				alpha = 1 / alpha - 1;
				R_new = r + (r - L * 255) * alpha;

				G_new = g + (g - L * 255) * alpha;

				B_new = b + (b - L * 255) * alpha;
			}
			else
			{
				alpha = Increment;
				R_new = L * 255 + (r - L * 255) * (1+alpha);

				G_new = L * 255 + (g - L * 255) * (1+alpha);

				B_new = L * 255 + (b - L * 255) * (1+alpha);
			}
			image.at(j, i).val[0] = B_new;
			image.at(j, i).val[1] = G_new;
			image.at(j, i).val[2] = R_new;
		}
	}
	imshow("image",image);
}
void main()
{
	image = imread("lena.png");
	src = image.clone();

	Increment_value = 100;

	namedWindow("image", 1);
	createTrackbar("饱和度", "image", &Increment_value, 200, on_Trackbar);

	on_Trackbar(Increment_value, 0);
	

	waitKey();
	image.release();
	src.release();

}