core: use matlab-style 1d fftShift in pc

modules/imgproc/src/phasecorr.cpp

@@ -372,17 +372,18 @@ static void fftShift(InputOutputArray _out)
 
     if(is_1d)
     {
+        int is_odd = (xMid > 0 && out.cols % 2 == 1) || (yMid > 0 && out.rows % 2 == 1);
         xMid = xMid + yMid;
 
         for(size_t i = 0; i < planes.size(); i++)
         {
             Mat tmp;
-            Mat half0(planes[i], Rect(0, 0, xMid, 1));
-            Mat half1(planes[i], Rect(xMid, 0, xMid, 1));
+            Mat half0(planes[i], Rect(0, 0, xMid + is_odd, 1));
+            Mat half1(planes[i], Rect(xMid + is_odd, 0, xMid, 1));
 
             half0.copyTo(tmp);
-            half1.copyTo(half0);
-            tmp.copyTo(half1);
+            half1.copyTo(planes[i](Rect(0, 0, xMid, 1)));
+            tmp.copyTo(planes[i](Rect(xMid, 0, xMid + is_odd, 1)));
         }
     }
     else

modules/imgproc/test/test_pc.cpp

@@ -86,4 +86,21 @@ void CV_PhaseCorrelatorTest::run( int )
 
 TEST(Imgproc_PhaseCorrelatorTest, accuracy) { CV_PhaseCorrelatorTest test; test.safe_run(); }
 
+TEST(Imgproc_PhaseCorrelatorTest, accuracy_1d_odd_fft) {
+    Mat r1 = Mat::ones(Size(129, 1), CV_64F)*255; // 129 will be completed to 135 before FFT
+    Mat r2 = Mat::ones(Size(129, 1), CV_64F)*255;
+
+    const int xShift = 10;
+
+    for(int i = 6; i < 20; i++)
+    {
+        r1.at<double>(i) = 1;
+        r2.at<double>(i + xShift) = 1;
+    }
+
+    Point2d phaseShift = phaseCorrelate(r1, r2);
+
+    ASSERT_NEAR(phaseShift.x, (double)xShift, .5);
+}
+
 }