photo: add Decolor() function

Signed-off-by: deadprogram <ron@hybridgroup.com>

ROADMAP.md

@@ -197,7 +197,7 @@ Your pull requests will be greatly appreciated!
     - [ ] [createTonemapDrago](https://docs.opencv.org/master/d6/df5/group__photo__hdr.html#ga72bf92bb6b8653ee4be650ac01cf50b6)
     - [ ] [createTonemapMantiuk](https://docs.opencv.org/master/d6/df5/group__photo__hdr.html#ga3b3f3bf083b7515802f039a6a70f2d21)
     - [ ] [createTonemapReinhard](https://docs.opencv.org/master/d6/df5/group__photo__hdr.html#gadabe7f6bf1fa96ad0fd644df9182c2fb)
-    - [ ] [decolor](https://docs.opencv.org/master/d4/d32/group__photo__decolor.html#ga4864d4c007bda5dacdc5e9d4ed7e222c)
+    - [X] [decolor](https://docs.opencv.org/master/d4/d32/group__photo__decolor.html#ga4864d4c007bda5dacdc5e9d4ed7e222c)
 
 - [ ] stitching. Images stitching
     - [ ] [Stitcher](https://docs.opencv.org/4.x/d2/d8d/classcv_1_1Stitcher.html)

photo.cpp

@@ -222,3 +222,12 @@ OpenCVResult PhotoInpaint(Mat src, Mat mask, Mat dst, float inpaint_radius, int
         return errorResult(e.code, e.what());
     }
 }
+
+OpenCVResult Decolor(Mat src, Mat grey, Mat boost) {
+    try {
+        cv::decolor(*src, *grey, *boost);
+        return successResult();
+    } catch(const cv::Exception& e) {
+        return errorResult(e.code, e.what());
+    }
+}

photo.go

@@ -317,3 +317,13 @@ const (
 func Inpaint(src Mat, mask Mat, dst *Mat, inpaintRadius float32, algorithmType InpaintMethods) error {
 	return OpenCVResult(C.PhotoInpaint(C.Mat(src.Ptr()), C.Mat(mask.Ptr()), C.Mat(dst.Ptr()), C.float(inpaintRadius), C.int(algorithmType)))
 }
+
+// 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
+//
+// For further details, please see:
+// https://docs.opencv.org/4.x/d4/d32/group__photo__decolor.html#ga4864d4c007bda5dacdc5e9d4ed7e222c
+func Decolor(src Mat, grey *Mat, boost *Mat) error {
+	return OpenCVResult(C.Decolor(src.p, grey.p, boost.p))
+}

photo.h

@@ -50,6 +50,7 @@ OpenCVResult PencilSketch(Mat src, Mat dst1, Mat dst2, float sigma_s, float sigm
 OpenCVResult Stylization(Mat src, Mat dst, float sigma_s, float sigma_r);
 
 OpenCVResult PhotoInpaint(Mat src, Mat mask, Mat dst, float inpaint_radius, int algorithm_type);
+OpenCVResult Decolor(Mat src, Mat grey, Mat boost);
 
 #ifdef __cplusplus
 }

photo_test.go

@@ -260,3 +260,29 @@ func TestInpaint(t *testing.T) {
 		t.Error("Invalid inpaint test")
 	}
 }
+
+func TestDecolor(t *testing.T) {
+	img := IMRead("images/face-detect.jpg", IMReadColor)
+	if img.Empty() {
+		t.Error("Invalid read of Mat in Decolor test")
+	}
+	defer img.Close()
+
+	grey := NewMat()
+	defer grey.Close()
+
+	boost := NewMat()
+	defer boost.Close()
+
+	if err := Decolor(img, &grey, &boost); err != nil {
+		t.Error("Error in Decolor test", err)
+	}
+
+	if grey.Empty() || img.Rows() != grey.Rows() || img.Cols() != grey.Cols() {
+		t.Error("Error in Decolor test")
+	}
+
+	if boost.Empty() || img.Rows() != boost.Rows() || img.Cols() != boost.Cols() {
+		t.Error("Error in Decolor test")
+	}
+}