fixed http://code.opencv.org/issues/3828

modules/core/src/stat.cpp

@@ -2587,6 +2587,11 @@ void cv::findNonZero( InputArray _src, OutputArray _idx )
     Mat src = _src.getMat();
     CV_Assert( src.type() == CV_8UC1 );
     int n = countNonZero(src);
+    if (n == 0)
+    {
+        _idx.release();
+        return;
+    }
     if( _idx.kind() == _InputArray::MAT && !_idx.getMatRef().isContinuous() )
         _idx.release();
     _idx.create(n, 1, CV_32SC2);

modules/core/test/test_arithm.cpp

@@ -1810,3 +1810,13 @@ TEST(MinMaxLoc, Mat_IntMax_Without_Mask)
     ASSERT_EQ(Point(0, 0), minLoc);
     ASSERT_EQ(Point(0, 0), maxLoc);
 }
+
+
+TEST(Core_FindNonZero, singular)
+{
+    Mat img(10, 10, CV_8U, Scalar::all(0));
+    vector<Point> pts, pts2(10);
+    findNonZero(img, pts);
+    findNonZero(img, pts2);
+    ASSERT_TRUE(pts.empty() && pts2.empty());
+}