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Intensity Windowing

Synopsis

Apply a linear intensity transform from a specified input range to a specified output range.

Results

output.png

Code

C++

#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkIntensityWindowingImageFilter.h"
#include "itkImageRegionIterator.h"

using ImageType = itk::Image<unsigned char, 2>;

static void
CreateImage(ImageType::Pointer image);

int
main()
{
  auto image = ImageType::New();
  CreateImage(image);

  using IntensityWindowingImageFilterType = itk::IntensityWindowingImageFilter<ImageType, ImageType>;

  auto filter = IntensityWindowingImageFilterType::New();
  filter->SetInput(image);
  filter->SetWindowMinimum(0);
  filter->SetWindowMaximum(100);
  filter->SetOutputMinimum(0);
  filter->SetOutputMaximum(255);
  filter->Update();

  itk::WriteImage(image, "output.png");

  return EXIT_SUCCESS;
}

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

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

  ImageType::RegionType region(start, size);

  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(10);

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

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

    ++imageIterator;
  }
}

Classes demonstrated

template<typename TInputImage, typename TOutputImage = TInputImage>
class IntensityWindowingImageFilter : public itk::UnaryFunctorImageFilter<TInputImage, TOutputImage, Functor::IntensityWindowingTransform<TInputImage::PixelType, TOutputImage::PixelType>>

Applies a linear transformation to the intensity levels of the input Image that are inside a user-defined interval. Values below this interval are mapped to a constant. Values over the interval are mapped to another constant.

IntensityWindowingImageFilter applies pixel-wise a linear transformation to the intensity values of input image pixels. The linear transformation is defined by the user in terms of the minimum and maximum values that the output image should have and the lower and upper limits of the intensity window of the input image. This operation is very common in visualization, and can also be applied as a convenient preprocessing operation for image segmentation.

All computations are performed in the precision of the input pixel’s RealType. Before assigning the computed value to the output pixel.

ITK Sphinx Examples:

• All ITK Sphinx Examples

• Intensity Windowing

See

RescaleIntensityImageFilter

See itk::IntensityWindowingImageFilter for additional documentation.