diff --git a/libraries/wavemap/include/wavemap/integrator/projection_model/projector_base.h b/libraries/wavemap/include/wavemap/integrator/projection_model/projector_base.h
index 4467021f5..69a0379d8 100644
--- a/libraries/wavemap/include/wavemap/integrator/projection_model/projector_base.h
+++ b/libraries/wavemap/include/wavemap/integrator/projection_model/projector_base.h
@@ -111,11 +111,6 @@ class ProjectorBase {
       const Transformation3D::RotationMatrix& R_C_W,
       const Point3D& t_W_C) const = 0;
 
-  Vector2D imageToIndexReal(const ImageCoordinates& image_coordinates) const;
-  const Vector2D& getIndexToImageScaleFactor() const {
-    return index_to_image_scale_factor_;
-  }
-
  protected:
   const Index2D dimensions_;
   const Vector2D index_to_image_scale_factor_;
@@ -125,6 +120,13 @@ class ProjectorBase {
 
   const ImageCoordinates min_image_coordinates_;
   const ImageCoordinates max_image_coordinates_;
+
+  Vector2D imageToIndexReal(const ImageCoordinates& image_coordinates) const;
+
+  // Give test 'imageToNearestIndicesAndOffsets' of gtest test suite
+  // 'Image2DProjectorTypedTest' access to private methods and members
+  template <typename T>
+  friend class Image2DProjectorTypedTest_imageToNearestIndicesAndOffsets_Test;
 };
 }  // namespace wavemap
 
diff --git a/libraries/wavemap/test/src/integrator/projection_model/test_image_projectors.cc b/libraries/wavemap/test/src/integrator/projection_model/test_image_projectors.cc
index 39b9fd158..794ccd2ca 100644
--- a/libraries/wavemap/test/src/integrator/projection_model/test_image_projectors.cc
+++ b/libraries/wavemap/test/src/integrator/projection_model/test_image_projectors.cc
@@ -408,7 +408,7 @@ TYPED_TEST(Image2DProjectorTypedTest, imageToNearestIndicesAndOffsets) {
           neighbox_idx & 0b10 ? index_upper[1] : index_lower[1]};
       const Index2D index_expected = index_rounded.cast<IndexElement>();
       const Vector2D offset_expected =
-          projector.getIndexToImageScaleFactor().cwiseProduct(index_rounded -
+          projector.index_to_image_scale_factor_.cwiseProduct(index_rounded -
                                                               index_real);
 
       EXPECT_EQ(indices(0, neighbox_idx), index_expected[0]);