diff --git a/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.h b/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.h
index eaf228884..2c3d434e8 100644
--- a/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.h
+++ b/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.h
@@ -305,8 +305,8 @@ class ITK_TEMPLATE_EXPORT ParzenWindowHistogramImageToImageMetric
                        PDFValueType *             parzenValues);
 
   /** Multiply the pdf entries by the given normalization factor. */
-  void
-  NormalizeJointPDF(JointPDFType * pdf, const double factor) const;
+  static void
+  NormalizeJointPDF(JointPDFType * pdf, const double factor);
 
   /** Compute marginal pdfs by summing over the joint pdf
    * direction = 0: fixed marginal pdf
diff --git a/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.hxx b/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.hxx
index 4d348518e..9e24ca20c 100644
--- a/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.hxx
+++ b/Common/CostFunctions/itkParzenWindowHistogramImageToImageMetric.hxx
@@ -24,6 +24,7 @@
 #include "itkBSplineDerivativeKernelFunction2.h"
 #include "itkImageLinearIteratorWithIndex.h"
 #include "itkImageScanlineIterator.h"
+#include <itkImageBufferRange.h>
 #include <vnl/vnl_math.h>
 #include <cassert>
 
@@ -606,19 +607,11 @@ ParzenWindowHistogramImageToImageMetric<TFixedImage, TMovingImage>::UpdateJointP
 template <typename TFixedImage, typename TMovingImage>
 void
 ParzenWindowHistogramImageToImageMetric<TFixedImage, TMovingImage>::NormalizeJointPDF(JointPDFType * pdf,
-                                                                                      const double   factor) const
+                                                                                      const double   factor)
 {
-  using JointPDFIteratorType = ImageScanlineIterator<JointPDFType>;
-  JointPDFIteratorType it(pdf, pdf->GetBufferedRegion());
-  const auto           castfac = static_cast<PDFValueType>(factor);
-  while (!it.IsAtEnd())
+  for (PDFValueType & pdfValue : ImageBufferRange(*pdf))
   {
-    while (!it.IsAtEndOfLine())
-    {
-      it.Value() *= castfac;
-      ++it;
-    }
-    it.NextLine();
+    pdfValue *= factor;
   }
 
 } // end NormalizeJointPDF()
diff --git a/Common/GTesting/CMakeLists.txt b/Common/GTesting/CMakeLists.txt
index a24713ece..9c60484a2 100644
--- a/Common/GTesting/CMakeLists.txt
+++ b/Common/GTesting/CMakeLists.txt
@@ -21,6 +21,7 @@ set(ELX_COMMON_GTEST_SOURCES
   itkImageRandomSamplerSparseMaskGTest.cxx
   itkImageSamplerGTest.cxx
   itkParameterMapInterfaceTest.cxx
+  itkParzenWindowHistogramImageToImageMetricGTest.cxx
 )
 
 if(USE_ImpactMetric)
diff --git a/Common/GTesting/itkParzenWindowHistogramImageToImageMetricGTest.cxx b/Common/GTesting/itkParzenWindowHistogramImageToImageMetricGTest.cxx
new file mode 100644
index 000000000..638d6b232
--- /dev/null
+++ b/Common/GTesting/itkParzenWindowHistogramImageToImageMetricGTest.cxx
@@ -0,0 +1,64 @@
+/*=========================================================================
+ *
+ *  Copyright UMC Utrecht and contributors
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *=========================================================================*/
+
+// First include the header file to be tested:
+#include "itkParzenWindowHistogramImageToImageMetric.h"
+#include <itkImageBufferRange.h>
+#include "GTesting/elxCoreMainGTestUtilities.h"
+#include <gtest/gtest.h>
+
+// The template to be tested.
+using itk::ParzenWindowHistogramImageToImageMetric;
+using elx::CoreMainGTestUtilities::CreateImageFilledWithSequenceOfNaturalNumbers;
+
+
+// Checks the protected member function NormalizeJointPDF.
+GTEST_TEST(ParzenWindowHistogramImageToImageMetric, NormalizeJointPDF)
+{
+  using ImageType = itk::Image<int>;
+  using ParzenWindowHistogramImageToImageMetricType = ParzenWindowHistogramImageToImageMetric<ImageType, ImageType>;
+
+  class DerivedMetric : ParzenWindowHistogramImageToImageMetricType
+  {
+  public:
+    static void
+    TestNormalizeJointPDF(const double factor)
+    {
+      const auto pdf = CreateImageFilledWithSequenceOfNaturalNumbers<PDFValueType>(itk::Size<>{ 4, 5 });
+
+      const itk::ImageBufferRange imageBufferRange(*pdf);
+
+      const std::vector<PDFValueType> originalPDFValues(imageBufferRange.cbegin(), imageBufferRange.cend());
+
+      ParzenWindowHistogramImageToImageMetricType::NormalizeJointPDF(pdf, factor);
+
+      auto originalPDFValueIterator = originalPDFValues.cbegin();
+
+      for (const PDFValueType pixelValue : imageBufferRange)
+      {
+        EXPECT_EQ(pixelValue, *originalPDFValueIterator * factor);
+        ++originalPDFValueIterator;
+      }
+    }
+  };
+
+  for (const auto factor : { 0.0, 0.5, 1.0 })
+  {
+    DerivedMetric::TestNormalizeJointPDF(factor);
+  }
+}
diff --git a/Components/Metrics/AdvancedMattesMutualInformation/itkParzenWindowMutualInformationImageToImageMetric.hxx b/Components/Metrics/AdvancedMattesMutualInformation/itkParzenWindowMutualInformationImageToImageMetric.hxx
index fd4ac720d..4dcfa7129 100644
--- a/Components/Metrics/AdvancedMattesMutualInformation/itkParzenWindowMutualInformationImageToImageMetric.hxx
+++ b/Components/Metrics/AdvancedMattesMutualInformation/itkParzenWindowMutualInformationImageToImageMetric.hxx
@@ -78,7 +78,7 @@ ParzenWindowMutualInformationImageToImageMetric<TFixedImage, TMovingImage>::GetV
   this->ComputePDFs(parameters);
 
   /** Normalize the pdfs: p = alpha h. */
-  this->NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
+  Superclass::NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
 
   /** Compute the fixed and moving marginal pdfs, by summing over the joint pdf. */
   this->ComputeMarginalPDF(this->m_JointPDF, this->m_FixedImageMarginalPDF, 0);
@@ -156,7 +156,7 @@ ParzenWindowMutualInformationImageToImageMetric<TFixedImage, TMovingImage>::GetV
   this->ComputePDFsAndPDFDerivatives(parameters);
 
   /** Normalize the pdfs: p = alpha h. */
-  this->NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
+  Superclass::NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
 
   /** Compute the fixed and moving marginal pdf by summing over the histogram. */
   this->ComputeMarginalPDF(this->m_JointPDF, this->m_FixedImageMarginalPDF, 0);
@@ -245,7 +245,7 @@ ParzenWindowMutualInformationImageToImageMetric<TFixedImage, TMovingImage>::GetV
   this->ComputePDFs(parameters);
 
   /** Normalize the joint histogram by alpha. */
-  this->NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
+  Superclass::NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
 
   /** Compute the fixed and moving marginal pdf by summing over the histogram. */
   this->ComputeMarginalPDF(this->m_JointPDF, this->m_FixedImageMarginalPDF, 0);
diff --git a/Components/Metrics/NormalizedMutualInformation/itkParzenWindowNormalizedMutualInformationImageToImageMetric.hxx b/Components/Metrics/NormalizedMutualInformation/itkParzenWindowNormalizedMutualInformationImageToImageMetric.hxx
index 183640f3d..43f1e52b5 100644
--- a/Components/Metrics/NormalizedMutualInformation/itkParzenWindowNormalizedMutualInformationImageToImageMetric.hxx
+++ b/Components/Metrics/NormalizedMutualInformation/itkParzenWindowNormalizedMutualInformationImageToImageMetric.hxx
@@ -146,7 +146,7 @@ ParzenWindowNormalizedMutualInformationImageToImageMetric<TFixedImage, TMovingIm
   this->ComputePDFs(parameters);
 
   /** Normalize the pdfs: p = alpha h */
-  this->NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
+  Superclass::NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
 
   /** Compute the fixed and moving marginal pdfs, by summing over the joint pdf */
   this->ComputeMarginalPDF(this->m_JointPDF, this->m_FixedImageMarginalPDF, 0);
@@ -186,7 +186,7 @@ ParzenWindowNormalizedMutualInformationImageToImageMetric<TFixedImage, TMovingIm
   this->ComputePDFsAndPDFDerivatives(parameters);
 
   /** Normalize the pdfs: p = alpha h*/
-  this->NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
+  Superclass::NormalizeJointPDF(this->m_JointPDF, this->m_Alpha);
 
   /** Compute the fixed and moving marginal pdf by summing over the histogram */
   this->ComputeMarginalPDF(this->m_JointPDF, this->m_FixedImageMarginalPDF, 0);