ENH: Improve warning messages (label numbers as ints instead of chars)

This filter is typically instantiated with unsigned char pixel type,
which leads to non-meaningful information being printed, such as:

WARNING: In C:\P\IPP\ITK-source\ITK\Modules\Filtering\ImageStatistics\include\itkLabelOverlapMeasuresImageFilter.hxx, line 233
LabelOverlapMeasuresImageFilter (000001FF7CF72F80): Label � not found.

WARNING: In C:\P\IPP\ITK-source\ITK\Modules\Filtering\ImageStatistics\include\itkLabelOverlapMeasuresImageFilter.hxx, line 233
LabelOverlapMeasuresImageFilter (000001FF7CF72F80): Label � not found.

WARNING: In C:\P\IPP\ITK-source\ITK\Modules\Filtering\ImageStatistics\include\itkLabelOverlapMeasuresImageFilter.hxx, line 233
LabelOverlapMeasuresImageFilter (000001FF7CF72F80): Label � not found.

WARNING: In C:\P\IPP\ITK-source\ITK\Modules\Filtering\ImageStatistics\include\itkLabelOverlapMeasuresImageFilter.hxx, line 233
LabelOverlapMeasuresImageFilter (000001FF7CF72F80): Label not found.

Modules/Filtering/ImageStatistics/include/itkLabelOverlapMeasuresImageFilter.h

@@ -196,13 +196,16 @@ class ITK_TEMPLATE_EXPORT LabelOverlapMeasuresImageFilter : public ImageSink<TLa
 protected:
   LabelOverlapMeasuresImageFilter();
   ~LabelOverlapMeasuresImageFilter() override = default;
+
+  /** Type to use for printing label values (e.g. in warnings). */
+  using PrintType = typename NumericTraits<LabelType>::PrintType;
+
   void
   PrintSelf(std::ostream & os, Indent indent) const override;
 
   void
   BeforeStreamedGenerateData() override;
 
-
   void
   ThreadedStreamedGenerateData(const RegionType &) override;
 

Modules/Filtering/ImageStatistics/include/itkLabelOverlapMeasuresImageFilter.hxx

@@ -174,7 +174,7 @@ LabelOverlapMeasuresImageFilter<TLabelImage>::GetTargetOverlap(LabelType label)
   auto mapIt = this->m_LabelSetMeasures.find(label);
   if (mapIt == this->m_LabelSetMeasures.end())
   {
-    itkWarningMacro("Label " << label << " not found.");
+    itkWarningMacro("Label " << static_cast<PrintType>(label) << " not found.");
     return 0.0;
   }
 
@@ -225,7 +225,7 @@ LabelOverlapMeasuresImageFilter<TLabelImage>::GetUnionOverlap(LabelType label) c
   auto mapIt = this->m_LabelSetMeasures.find(label);
   if (mapIt == this->m_LabelSetMeasures.end())
   {
-    itkWarningMacro("Label " << label << " not found.");
+    itkWarningMacro("Label " << static_cast<PrintType>(label) << " not found.");
     return 0.0;
   }
 
@@ -292,7 +292,7 @@ LabelOverlapMeasuresImageFilter<TLabelImage>::GetVolumeSimilarity(LabelType labe
   auto mapIt = this->m_LabelSetMeasures.find(label);
   if (mapIt == this->m_LabelSetMeasures.end())
   {
-    itkWarningMacro("Label " << label << " not found.");
+    itkWarningMacro("Label " << static_cast<PrintType>(label) << " not found.");
     return 0.0;
   }
   RealType value = 2.0 *
@@ -335,7 +335,7 @@ LabelOverlapMeasuresImageFilter<TLabelImage>::GetFalseNegativeError(LabelType la
   auto mapIt = this->m_LabelSetMeasures.find(label);
   if (mapIt == this->m_LabelSetMeasures.end())
   {
-    itkWarningMacro("Label " << label << " not found.");
+    itkWarningMacro("Label " << static_cast<PrintType>(label) << " not found.");
     return 0.0;
   }
 
@@ -391,7 +391,7 @@ LabelOverlapMeasuresImageFilter<TLabelImage>::GetFalsePositiveError(LabelType la
   auto mapIt = this->m_LabelSetMeasures.find(label);
   if (mapIt == this->m_LabelSetMeasures.end())
   {
-    itkWarningMacro("Label " << label << " not found.");
+    itkWarningMacro("Label " << static_cast<PrintType>(label) << " not found.");
     return 0.0;
   }
 
@@ -446,7 +446,7 @@ LabelOverlapMeasuresImageFilter<TLabelImage>::GetFalseDiscoveryRate(LabelType la
   auto mapIt = this->m_LabelSetMeasures.find(label);
   if (mapIt == this->m_LabelSetMeasures.end())
   {
-    itkWarningMacro("Label " << label << " not found.");
+    itkWarningMacro("Label " << static_cast<PrintType>(label) << " not found.");
     return 0.0;
   }