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Binary XOR Two Images

Synopsis

Binary XOR (exclusive OR) two images.

Results

input1.png

input2.png

output.png

Code

C++

#include "itkImage.h"
#include "itkSimpleFilterWatcher.h"
#include "itkXorImageFilter.h"
#include "itkImageRegionIterator.h"
#include "itkImageFileWriter.h"

using ImageType = itk::Image<unsigned char, 2>;
static void
CreateImage1(ImageType::Pointer image);
static void
CreateImage2(ImageType::Pointer image);

int
main()
{
  auto image1 = ImageType::New();
  CreateImage1(image1);

  auto image2 = ImageType::New();
  CreateImage2(image2);

  using XorImageFilterType = itk::XorImageFilter<ImageType>;
  auto xorFilter = XorImageFilterType::New();
  xorFilter->SetInput1(image1);
  xorFilter->SetInput2(image2);
  xorFilter->Update();

  itk::WriteImage(xorFilter->GetOutput(), "output.png");

  return EXIT_SUCCESS;
}

void
CreateImage1(ImageType::Pointer image)
{
  ImageType::IndexType start;
  start.Fill(0);

  ImageType::SizeType size;
  size.Fill(100);

  ImageType::RegionType region;
  region.SetSize(size);
  region.SetIndex(start);

  image->SetRegions(region);
  image->Allocate();

  itk::ImageRegionIterator<ImageType> imageIterator(image, region);

  while (!imageIterator.IsAtEnd())
  {
    if (imageIterator.GetIndex()[0] < 70)
    {
      imageIterator.Set(255);
    }
    else
    {
      imageIterator.Set(0);
    }

    ++imageIterator;
  }
}

void
CreateImage2(ImageType::Pointer image)
{
  ImageType::IndexType start;
  start.Fill(0);

  ImageType::SizeType size;
  size.Fill(100);

  ImageType::RegionType region;
  region.SetSize(size);
  region.SetIndex(start);

  image->SetRegions(region);
  image->Allocate();

  itk::ImageRegionIterator<ImageType> imageIterator(image, region);

  while (!imageIterator.IsAtEnd())
  {
    if (imageIterator.GetIndex()[0] > 30)
    {
      imageIterator.Set(255);
    }
    else
    {
      imageIterator.Set(0);
    }

    ++imageIterator;
  }
}

Classes demonstrated

template<typename TInputImage1, typename TInputImage2 = TInputImage1, typename TOutputImage = TInputImage1>
class XorImageFilter : public itk::BinaryGeneratorImageFilter<TInputImage1, TInputImage2, TOutputImage>

Computes the XOR bitwise operator pixel-wise between two images.

This class is templated over the types of the two input images and the type of the output image. Numeric conversions (castings) are done by the C++ defaults.

Since the bitwise XOR operation is only defined in C++ for integer types, the images passed to this filter must comply with the requirement of using integer pixel type.

The total operation over one pixel will be

output_pixel = static_cast<OutputPixelType>( input1_pixel ^ input2_pixel )

Where “^” is the boolean XOR operator in C++.

ITK Sphinx Examples:

• All ITK Sphinx Examples

• Binary XOR Two Images

See itk::XorImageFilter for additional documentation.