Merge pull request #3851 from ellbur:findTransformECC-initialize-bug

modules/video/perf/perf_ecc.cpp

@@ -67,5 +67,5 @@ PERF_TEST_P(TransformationType, findTransformECC, /*testing::ValuesIn(MotionType
         findTransformECC(templateImage, img, warpMat, transform_type,
             TermCriteria(TermCriteria::COUNT+TermCriteria::EPS, 5, -1));
     }
-    SANITY_CHECK(warpMat, 1e-3);
+    SANITY_CHECK(warpMat, 3e-3);
 }

modules/video/src/ecc.cpp

@@ -465,6 +465,7 @@ double cv::findTransformECC(InputArray templateImage,
         meanStdDev(templateFloat, tmpMean, tmpStd, imageMask);
 
         subtract(imageWarped,   imgMean, imageWarped, imageMask);//zero-mean input
+        templateZM = Mat::zeros(templateZM.rows, templateZM.cols, templateZM.type());
         subtract(templateFloat, tmpMean, templateZM,  imageMask);//zero-mean template
 
         const double tmpNorm = std::sqrt(countNonZero(imageMask)*(tmpStd.val[0])*(tmpStd.val[0]));