In this source code /modules/imgproc/src/phasecorr.cpp,
I think std::sqrt should be applied to the below lines.
here dataDst[0] = dataSrc[0]*dataSrc[0];
here dataDst[(rows-1)*stepDst] = dataSrc[(rows-1)*stepSrc]*dataSrc[(rows-1)*stepSrc];
here dataDst[0] = dataSrc[0]*dataSrc[0];
here dataDst[j1] = dataSrc[j1]*dataSrc[j1];
here dataDst[0] = dataSrc[0]*dataSrc[0];
here dataDst[(rows-1)*stepDst] = dataSrc[(rows-1)*stepSrc]*dataSrc[(rows-1)*stepSrc];
here dataDst[0] = dataSrc[0]*dataSrc[0];
here dataDst[j1] = dataSrc[j1]*dataSrc[j1];