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Convert an ITK Gray Scale Image to CV Mat

Synopsis

Convert an itk::Image (gray scale) to OpenCV cv::Mat.

Results

Input image

Output image

Code

C++

#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkOpenCVImageBridge.h"

// includes from OpenCV
#include "opencv2/opencv.hpp" // cv::imwrite


int
main(int argc, char * argv[])
{
  if (argc != 3)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0];
    std::cerr << "<InputFileName> <OutputFileName>";
    std::cerr << std::endl;
    return EXIT_FAILURE;
  }

  constexpr unsigned int Dimension = 2;

  using PixelType = unsigned char;
  using ImageType = itk::Image<PixelType, Dimension>;

  using ReaderType = itk::ImageFileReader<ImageType>;
  auto reader = ReaderType::New();
  reader->SetFileName(argv[1]);

  try
  {
    reader->Update();
  }
  catch (const itk::ExceptionObject & error)
  {
    std::cerr << "Error: " << error << std::endl;
    return EXIT_FAILURE;
  }

  cv::Mat img = itk::OpenCVImageBridge::ITKImageToCVMat<ImageType>(reader->GetOutput());

  cv::imwrite(argv[2], img);

  return EXIT_SUCCESS;
}

Classes demonstrated

class OpenCVImageBridge

This class provides static methods to convert between OpenCV images and itk::Image.

This class provides methods for the following conversions: IplImage -> itk::Image cv::Mat -> itk::Image itk::Image -> IplImage itk::Image -> cv::Mat

Each method is templated over the type of itk::Image used. The conversions copy the data and convert between types if necessary.

See itk::OpenCVImageBridge for additional documentation.