Merge pull request #10258 from savuor:fix/kmeans_channels

* kmeans: number of channels in _centers fixed

* fixedType() is checked now

modules/core/src/kmeans.cpp

@@ -458,7 +458,12 @@ double cv::kmeans( InputArray _data, int K,
         {
             best_compactness = compactness;
             if( _centers.needed() )
-                centers.copyTo(_centers);
+            {
+                Mat reshaped = centers;
+                if(_centers.fixedType() && _centers.channels() == dims)
+                    reshaped = centers.reshape(dims);
+                reshaped.copyTo(_centers);
+            }
             _labels.copyTo(best_labels);
         }
     }

samples/cpp/kmeans.cpp

@@ -37,7 +37,7 @@ int main( int /*argc*/, char** /*argv*/ )
         Mat points(sampleCount, 1, CV_32FC2), labels;
 
         clusterCount = MIN(clusterCount, sampleCount);
-        Mat centers;
+        std::vector<Point2f> centers;
 
         /* generate random sample from multigaussian distribution */
         for( k = 0; k < clusterCount; k++ )
@@ -65,9 +65,9 @@ int main( int /*argc*/, char** /*argv*/ )
             Point ipt = points.at<Point2f>(i);
             circle( img, ipt, 2, colorTab[clusterIdx], FILLED, LINE_AA );
         }
-        for (i = 0; i < centers.rows; ++i)
+        for (i = 0; i < (int)centers.size(); ++i)
         {
-            Point2f c = centers.at<Point2f>(i);
+            Point2f c = centers[i];
             circle( img, c, 40, colorTab[i], 1, LINE_AA );
         }
         cout << "Compactness: " << compactness << endl;