STYLE: Replace char with signed char as itk::Image argument in tests

Replaced `itk::Image<char` with `itk::Image<signed char`, in all "itk*Test*.cxx"
source files. Removed pixel type alias `InputDataType = char` from
itkAntiAliasBinaryImageFilterTest, and directly used `signed char` instead.

The use of `char` as `TPixel` argument in tests appears to triggers test
failures, when compiling with an unsigned default `char` type (GCC option
`-funsigned-char` or MSVC option `/J`), for example:

    [ RUN      ] FrequencyIterators.Even2D
    Unequal images, with 29 unequal pixels
    test/itkFrequencyIteratorsGTest.cxx:260: Failure
    Value of: fullAndHermitian
    Actual: false
    Expected: true

It appears clearer to explicitly specify that the pixel type should be signed,
by using `signed char` instead.

Author: N-Dekker

Modules/Core/Common/test/itkBSplineInterpolationWeightFunctionTest.cxx

@@ -274,7 +274,7 @@ itkBSplineInterpolationWeightFunctionTest(int, char *[])
     using KernelType = itk::BSplineKernelFunction<SplineOrder>;
     auto kernel = KernelType::New();
 
-    using ImageType = itk::Image<char, SpaceDimension>;
+    using ImageType = itk::Image<signed char, SpaceDimension>;
     auto                        image = ImageType::New();
     const ImageType::RegionType region{ startIndex, size };
 

Modules/Core/Common/test/itkConstNeighborhoodIteratorWithOnlyIndexTest.cxx

@@ -452,7 +452,7 @@ int
 itkConstNeighborhoodIteratorWithOnlyIndexTest(int, char *[])
 {
   std::cout << "*** Testing with itk::Image" << std::endl << std::endl;
-  if (itkConstNeighborhoodIteratorWithOnlyIndexTestRun<itk::Image<char, 4>>() == EXIT_FAILURE)
+  if (itkConstNeighborhoodIteratorWithOnlyIndexTestRun<itk::Image<signed char, 4>>() == EXIT_FAILURE)
   {
     std::cerr << "XXX Failed with itk::Image XXX" << std::endl;
     return EXIT_FAILURE;

Modules/Core/Common/test/itkImageAlgorithmCopyTest.cxx

@@ -118,7 +118,7 @@ AverageTestCopy(typename TImage::SizeType & size)
 int
 itkImageAlgorithmCopyTest(int, char *[])
 {
-  using ImageType3D = itk::Image<char, 3>;
+  using ImageType3D = itk::Image<signed char, 3>;
   auto size3d = ImageType3D::SizeType::Filled(16);
   AverageTestCopy<ImageType3D>(size3d);
 
@@ -131,7 +131,7 @@ itkImageAlgorithmCopyTest(int, char *[])
   size3d.Fill(128);
   AverageTestCopy<ImageType3D>(size3d);
 
-  using ImageType2D = itk::Image<char, 2>;
+  using ImageType2D = itk::Image<signed char, 2>;
   auto size2d = ImageType2D::SizeType::Filled(16);
   AverageTestCopy<ImageType2D>(size2d);
 

Modules/Core/Common/test/itkImageRegionConstIteratorWithOnlyIndexTest.cxx

@@ -189,7 +189,7 @@ itkImageRegionConstIteratorWithOnlyIndexTest(int, char *[])
 
   {
     std::cout << "Testing with Image< char, 3 >... " << std::endl;
-    itkImageRegionConstIteratorWithOnlyIndexTestIteratorTester<itk::Image<char, 3>> Tester;
+    itkImageRegionConstIteratorWithOnlyIndexTestIteratorTester<itk::Image<signed char, 3>> Tester;
     if (Tester.TestConstIterator() == false)
     {
       testPassed = false;

Modules/Core/Common/test/itkImageVectorOptimizerParametersHelperTest.cxx

@@ -142,7 +142,7 @@ itkImageVectorOptimizerParametersHelperTest(int, char *[])
   ITK_TRY_EXPECT_EXCEPTION(params.MoveDataPointer(array.data_block()));
 
   // Test setting an image of wrong type
-  using BadImageType = itk::Image<char, 2>;
+  using BadImageType = itk::Image<signed char, 2>;
   auto badImage = BadImageType::New();
   ITK_TRY_EXPECT_EXCEPTION(params.SetParametersObject(badImage));
 

Modules/Core/Common/test/itkMultiThreaderParallelizeArrayTest.cxx

@@ -66,7 +66,7 @@ itkMultiThreaderParallelizeArrayTest(int argc, char * argv[])
   constexpr unsigned int    size = 1029;
   std::vector<unsigned int> vec(size);
 
-  using SomeProcessObject = itk::AbsImageFilter<itk::Image<char>, itk::Image<char>>;
+  using SomeProcessObject = itk::AbsImageFilter<itk::Image<signed char>, itk::Image<signed char>>;
   auto progressPO = SomeProcessObject::New();
   auto showProgress = ShowProgress::New();
   progressPO->AddObserver(itk::ProgressEvent(), showProgress);

Modules/Core/Common/test/itkSimpleFilterWatcherTest.cxx

@@ -85,7 +85,7 @@ itkSimpleFilterWatcherTest(int, char *[])
 {
   // Test out the code
   using WatcherType = itk::SimpleFilterWatcher;
-  using ImageType = itk::Image<char, 3>;
+  using ImageType = itk::Image<signed char, 3>;
   using FilterType = itk::TanHelperImageFilter<ImageType, ImageType>;
   auto         filter = FilterType::New();
   const char * comment = "comment";

Modules/Filtering/AntiAlias/test/itkAntiAliasBinaryImageFilterTest.cxx

@@ -48,9 +48,9 @@ sphere(float x, float y, float z)
 }
 
 void
-evaluate_function(itk::Image<char, 3> * im, float (*f)(float, float, float))
+evaluate_function(itk::Image<signed char, 3> * im, float (*f)(float, float, float))
 {
-  itk::Image<char, 3>::IndexType idx;
+  itk::Image<signed char, 3>::IndexType idx;
 
   for (int z = 0; z < V_DEPTH; ++z)
   {
@@ -88,8 +88,7 @@ itkAntiAliasBinaryImageFilterTest(int argc, char * argv[])
   }
   const char * outputImage = argv[1];
 
-  using InputDataType = char;
-  using BinaryImageType = itk::Image<InputDataType, 3>;
+  using BinaryImageType = itk::Image<signed char, 3>;
   using RealImageType = itk::Image<float, 3>;
 
   const itk::AntiAliasBinaryImageFilter<BinaryImageType, RealImageType>::Pointer antialiaser =

Modules/Filtering/ImageCompose/test/itkJoinImageFilterTest.cxx

@@ -29,7 +29,7 @@ itkJoinImageFilterTest(int, char *[])
   constexpr unsigned int myDimension = 2;
 
   // Declare the types of the images
-  using myImageType1 = itk::Image<char, myDimension>;
+  using myImageType1 = itk::Image<signed char, myDimension>;
   using myImageType2 = itk::Image<itk::Vector<unsigned short, 2>, myDimension>;
   using myImageType3 = itk::Image<itk::RGBAPixel<short>, myDimension>;
 

Modules/Filtering/ImageFrequency/test/itkFrequencyIteratorsGTest.cxx

@@ -105,7 +105,7 @@ template <typename TOutputImageType>
 static typename TOutputImageType::Pointer
 CreateImage(unsigned int size)
 {
-  using ImageType = itk::Image<char, TOutputImageType::ImageDimension>;
+  using ImageType = itk::Image<signed char, TOutputImageType::ImageDimension>;
   auto imageSize = ImageType::SizeType::Filled(size);
   using RandomImageSourceType = itk::RandomImageSource<ImageType>;
   auto randomImageSource = RandomImageSourceType::New();