imgproc: add EMD()

Signed-off-by: deadprogram <[email protected]>

ROADMAP.md

@@ -68,8 +68,7 @@ Your pull requests will be greatly appreciated!
     - [ ] ColorMaps in OpenCV
     - [ ] Planar Subdivision
     - [ ] **Histograms  - WORK STARTED** The following functions still need implementation:
-        - [ ] [EMD](https://docs.opencv.org/master/d6/dc7/group__imgproc__hist.html#ga902b8e60cc7075c8947345489221e0e0)
-        - [ ] [wrapperEMD](https://docs.opencv.org/master/d6/dc7/group__imgproc__hist.html#ga31fdda0864e64ca6b9de252a2611758b)
+        - [X] [EMD](https://docs.opencv.org/master/d6/dc7/group__imgproc__hist.html#ga902b8e60cc7075c8947345489221e0e0)
 
     - [ ] **Structural Analysis and Shape Descriptors - WORK STARTED** The following functions still need implementation:
         - [ ] [fitEllipse](https://docs.opencv.org/master/d3/dc0/group__imgproc__shape.html#gaf259efaad93098103d6c27b9e4900ffa)

imgproc.cpp

@@ -76,6 +76,10 @@ double CompareHist(Mat hist1, Mat hist2, int method) {
     return cv::compareHist(*hist1, *hist2, method);
 }
 
+float EMD(Mat sig1, Mat sig2, int distType) {
+    return cv::EMD(*sig1, *sig2, distType);
+}
+
 struct RotatedRect FitEllipse(PointVector pts)
 {
     cv::RotatedRect bRect = cv::fitEllipse(*pts);

imgproc.go

@@ -176,6 +176,14 @@ func CompareHist(hist1 Mat, hist2 Mat, method HistCompMethod) float32 {
 	return float32(C.CompareHist(hist1.p, hist2.p, C.int(method)))
 }
 
+// EMD Computes the "minimal work" distance between two weighted point configurations.
+//
+// For further details, please see:
+// https://docs.opencv.org/4.x/d6/dc7/group__imgproc__hist.html#ga902b8e60cc7075c8947345489221e0e0
+func EMD(signature1, signature2 Mat, typ DistanceTypes) float32 {
+	return float32(C.EMD(signature1.p, signature2.p, C.int(typ)))
+}
+
 // ClipLine clips the line against the image rectangle.
 // For further details, please see:
 // https://docs.opencv.org/master/d6/d6e/group__imgproc__draw.html#gaf483cb46ad6b049bc35ec67052ef1c2c

imgproc.h

@@ -23,6 +23,7 @@ void EqualizeHist(Mat src, Mat dst);
 void CalcHist(struct Mats mats, IntVector chans, Mat mask, Mat hist, IntVector sz, FloatVector rng, bool acc);
 void CalcBackProject(struct Mats mats, IntVector chans, Mat hist, Mat backProject, FloatVector rng, bool uniform);
 double CompareHist(Mat hist1, Mat hist2, int method);
+float EMD(Mat sig1, Mat sig2, int distType);
 void ConvexHull(PointVector points, Mat hull, bool clockwise, bool returnPoints);
 void ConvexityDefects(PointVector points, Mat hull, Mat result);
 void BilateralFilter(Mat src, Mat dst, int d, double sc, double ss);

imgproc_test.go

@@ -1412,6 +1412,52 @@ func TestCompareHist(t *testing.T) {
 
 }
 
+func TestEMD(t *testing.T) {
+	img := IMRead("images/face-detect.jpg", IMReadUnchanged)
+	if img.Empty() {
+		t.Error("Invalid read of Mat in CompareHist test")
+	}
+	defer img.Close()
+
+	hist1 := NewMat()
+	defer hist1.Close()
+
+	hist2 := NewMat()
+	defer hist2.Close()
+
+	mask := NewMat()
+	defer mask.Close()
+
+	CalcHist([]Mat{img}, []int{0, 1}, mask, &hist1, []int{30, 32}, []float64{0.0, 180.0, 0.0, 255.0}, false)
+	CalcHist([]Mat{img}, []int{0, 1}, mask, &hist2, []int{30, 32}, []float64{0.0, 180.0, 0.0, 255.0}, false)
+
+	sig1 := NewMatWithSize(30*32, 3, MatTypeCV32FC1)
+	defer sig1.Close()
+
+	sig2 := NewMatWithSize(30*32, 3, MatTypeCV32FC1)
+	defer sig2.Close()
+
+	for h := 0; h < 30; h++ {
+		for s := 0; s < 32; s++ {
+			val := hist1.GetFloatAt(h, s)
+			sig1.SetFloatAt(h*32+s, 0, val)
+			sig1.SetFloatAt(h*32+s, 1, float32(h))
+			sig1.SetFloatAt(h*32+s, 2, float32(s))
+
+			val = hist2.GetFloatAt(h, s)
+			sig2.SetFloatAt(h*32+s, 0, val)
+			sig2.SetFloatAt(h*32+s, 1, float32(h))
+			sig2.SetFloatAt(h*32+s, 2, float32(s))
+		}
+	}
+
+	sim := EMD(sig1, sig2, DistL2)
+	if (1-sim)*100 < 99.9 {
+		t.Error("Invalid EMD test", (1-sim)*100)
+	}
+
+}
+
 func TestDrawing(t *testing.T) {
 	img := NewMatWithSize(150, 150, MatTypeCV8U)
 	if img.Empty() {