add color_boost + doc

modules/photo/doc/decolor.rst

+Decolorization
+==============
+
+.. highlight:: cpp
+
+decolor
+-------
+
+Transforms a color image to a grayscale image. It is a basic tool in digital printing, stylized black-and-white photograph rendering, and in many single channel image processing applications.
+
+.. ocv:function:: void decolor( InputArray src, OutputArray grayscale, OutputArray color_boost )
+
+    :param src: Input 8-bit 3-channel image.
+
+    :param grayscale: Output 8-bit 1-channel image.
+
+    :param color_boost: Output 8-bit 3-channel image.
+
+This function is to be applied on color images.
+

modules/photo/include/opencv2/photo.hpp

@@ -288,7 +288,7 @@ public:
 
 CV_EXPORTS_W Ptr<MergeRobertson> createMergeRobertson();
 
-CV_EXPORTS_W void decolor(InputArray src, OutputArray grayscale);
+CV_EXPORTS_W void decolor(InputArray src, OutputArray grayscale, OutputArray color_boost);
 
 } // cv
 

modules/photo/src/contrast_preserve.cpp

@@ -17,14 +17,17 @@ int rounding(double a)
 	return int(a + 0.5);
 }
 
-void cv::decolor(InputArray _src, OutputArray _dst)
+void cv::decolor(InputArray _src, OutputArray _dst, OutputArray _boost)
 {
-	Mat I = _src.getMat();
+    Mat I = _src.getMat();
     _dst.create(I.size(), CV_8UC1);
     Mat dst = _dst.getMat();
 
-    if(!I.data )      
-	{
+    _boost.create(I.size(), CV_8UC3);
+    Mat color_boost = _boost.getMat();
+
+    if(!I.data )
+    {
 		cout <<  "Could not open or find the image" << endl ;
 		return;
 	}
@@ -162,5 +165,40 @@ void cv::decolor(InputArray _src, OutputArray _dst)
 
 	Gray.convertTo(dst,CV_8UC1,255);
 
+    ///////////////////////////////////       Contrast Boosting   /////////////////////////////////
+	
+	Mat lab = Mat(img.size(),CV_8UC3);
+	Mat color = Mat(img.size(),CV_8UC3);
+	Mat l = Mat(img.size(),CV_8UC1);
+	Mat a = Mat(img.size(),CV_8UC1);
+	Mat b = Mat(img.size(),CV_8UC1);
+
+	cvtColor(I,lab,COLOR_BGR2Lab);
+
+	int h1 = img.size().height;
+	int w1 = img.size().width;
+
+	for(int i =0;i<h1;i++)
+		for(int j=0;j<w1;j++)
+		{
+			l.at<uchar>(i,j) = lab.at<uchar>(i,j*3+0);
+			a.at<uchar>(i,j) = lab.at<uchar>(i,j*3+1);
+			b.at<uchar>(i,j) = lab.at<uchar>(i,j*3+2);
+		}
 	
+	for(int i =0;i<h1;i++)
+		for(int j=0;j<w1;j++)
+		{
+			l.at<uchar>(i,j) = 255.0*Gray.at<float>(i,j);
+		}
+
+	for(int i =0;i<h1;i++)
+		for(int j=0;j<w1;j++)
+		{
+			lab.at<uchar>(i,j*3+0) = l.at<uchar>(i,j);
+			lab.at<uchar>(i,j*3+1) = a.at<uchar>(i,j);
+			lab.at<uchar>(i,j*3+2) = b.at<uchar>(i,j);
+		}
+
+	cvtColor(lab,color_boost,COLOR_Lab2BGR);
 }

modules/photo/test/test_decolor.cpp

@@ -16,19 +16,24 @@ TEST(Photo_Decolor, regression)
 {
         string folder = string(cvtest::TS::ptr()->get_data_path()) + "decolor/";
         string original_path = folder + "color_image_1.png";
-        string expected_path = folder + "grayscale_image_1.png";
+        string expected_path1 = folder + "grayscale_image_1.png";
+        string expected_path2 = folder + "color_boost_image_1.png";
 
         Mat original = imread(original_path, IMREAD_COLOR);
-        Mat expected = imread(expected_path, IMREAD_GRAYSCALE);
+        Mat expected1 = imread(expected_path1, IMREAD_GRAYSCALE);
+        Mat expected2 = imread(expected_path2, IMREAD_COLOR);
 
         ASSERT_FALSE(original.empty()) << "Could not load input image " << original_path;
-        ASSERT_FALSE(expected.empty()) << "Could not load reference image " << expected_path;
+        ASSERT_FALSE(expected1.empty()) << "Could not load reference image " << expected_path1;
+        ASSERT_FALSE(expected2.empty()) << "Could not load reference image " << expected_path2;
 
-        Mat result;
-        decolor(original, result);
+        Mat grayscale, color_boost;
+        decolor(original, grayscale, color_boost);
 
-        DUMP(result, expected_path + ".res.png");
+        DUMP(grayscale, expected_path1 + ".grayscale.png");
+        DUMP(color_boost, expected_path2 + ".color_boost.png");
 
-        ASSERT_EQ(0, norm(result != expected));
+        ASSERT_EQ(0, norm(grayscale != expected1));
+        ASSERT_EQ(0, norm(color_boost != expected2));
 }