ITK 图像下采样(ResampleImageFilter和ShrinkImageFilter)

1、使用 itk::ResampleImageFilter

#include "itkImage.h"
#include "itkResampleImageFilter.h"

constexpr unsigned int Dimension = 2;
using PixelType = unsigned char;
using ImageType = itk::Image;

int main()
{
    // 创建图像
    ImageType::Pointer inputImage = ImageType::New();

    // 设置图像信息，分配内存等
    // ...

    // 创建 ResampleImageFilter
    using ResampleFilterType = itk::ResampleImageFilter;
    ResampleFilterType::Pointer resampler = ResampleFilterType::New();

    // 设置输入图像
    resampler->SetInput(inputImage);

    // 设置缩放因子，这里设置为每个维度缩小一半
    ResampleFilterType::SpacingType spacing = inputImage->GetSpacing();
    for (unsigned int i = 0; i < Dimension; ++i)
    {
        spacing[i] *= 2.0;  // 缩小一半
    }
    resampler->SetOutputSpacing(spacing);

    // 设置插值方法
    resampler->SetInterpolator(itk::sitkLinear);

    // 执行下采样
    try
    {
        resampler->Update();
    }
    catch (const itk::ExceptionObject & exc)
    {
        std::cerr << "Exception caught: " << exc << std::endl;
        return EXIT_FAILURE;
    }

    // 获取下采样后的图像
    ImageType::Pointer outputImage = resampler->GetOutput();

    // 处理下采样后的图像，例如保存到文件
    // ...

    return EXIT_SUCCESS;
}

2、使用 itk::ShrinkImageFilter

#include "itkImage.h"
#include "itkShrinkImageFilter.h"

constexpr unsigned int Dimension = 2;
using PixelType = unsigned char;
using ImageType = itk::Image;

int main()
{
    // 创建图像
    ImageType::Pointer inputImage = ImageType::New();

    // 设置图像信息，分配内存等
    // ...

    // 创建 ShrinkImageFilter
    using ShrinkFilterType = itk::ShrinkImageFilter;
    ShrinkFilterType::Pointer shrinker = ShrinkFilterType::New();

    // 设置输入图像
    shrinker->SetInput(inputImage);

    // 设置缩小因子，这里设置为每个维度缩小一半
    ShrinkFilterType::ShrinkFactorsType shrinkFactors;
    shrinkFactors.Fill(2);  // 缩小一半
    shrinker->SetShrinkFactors(shrinkFactors);

    // 执行下采样
    try
    {
        shrinker->Update();
    }
    catch (const itk::ExceptionObject & exc)
    {
        std::cerr << "Exception caught: " << exc << std::endl;
        return EXIT_FAILURE;
    }

    // 获取下采样后的图像
    ImageType::Pointer outputImage = shrinker->GetOutput();

    // 处理下采样后的图像，例如保存到文件
    // ...

    return EXIT_SUCCESS;
}