message: Add some useful input assertions to PSNR function
  Input arrays must be depth CV_8U and of identical size.
diff: @@ -4150,7 +4150,10 @@ double cv::PSNR(InputArray _src1, InputArray _src2)
  {
  CV_INSTRUMENT_REGION()
  - CV_Assert( _src1.depth() == CV_8U );
  + //Input arrays must have depth CV_8U and be of identical size
  + CV_Assert( _src1.depth() == CV_8U && _src2.depth() == CV_8U );
  + CV_Assert( _src1.rows() == _src2.rows() && _src1.cols() == _src2.cols() && _src1.dims() == _src2.dims() );
  +
  double diff = std::sqrt(norm(_src1, _src2, NORM_L2SQR)/(_src1.total()*_src1.channels()));
  return 20*log10(255./(diff+DBL_EPSILON));
  }
  