Merge pull request #7966 from Tetragramm:Issue#4235

modules/imgproc/src/matchcontours.cpp

@@ -50,6 +50,7 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
     double eps = 1.e-5;
     double mmm;
     double result = 0;
+    bool anyA = false, anyB = false;
 
     HuMoments( moments(contour1), ma );
     HuMoments( moments(contour2), mb );
@@ -62,6 +63,11 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
             double ama = fabs( ma[i] );
             double amb = fabs( mb[i] );
 
+            if (ama > 0)
+                anyA = true;
+            if (amb > 0)
+                anyB = true;
+
             if( ma[i] > 0 )
                 sma = 1;
             else if( ma[i] < 0 )
@@ -90,6 +96,11 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
             double ama = fabs( ma[i] );
             double amb = fabs( mb[i] );
 
+            if (ama > 0)
+                anyA = true;
+            if (amb > 0)
+                anyB = true;
+
             if( ma[i] > 0 )
                 sma = 1;
             else if( ma[i] < 0 )
@@ -118,6 +129,11 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
             double ama = fabs( ma[i] );
             double amb = fabs( mb[i] );
 
+            if (ama > 0)
+                anyA = true;
+            if (amb > 0)
+                anyB = true;
+
             if( ma[i] > 0 )
                 sma = 1;
             else if( ma[i] < 0 )
@@ -145,6 +161,12 @@ double cv::matchShapes(InputArray contour1, InputArray contour2, int method, dou
         CV_Error( CV_StsBadArg, "Unknown comparison method" );
     }
 
+    //If anyA and anyB are both true, the result is correct.
+    //If anyA and anyB are both false, the distance is 0, perfect match.
+    //If only one is true, then it's a false 0 and return large error.
+    if (anyA != anyB)
+        result = DBL_MAX;
+
     return result;
 }