VTK_Learning_图像像素的访问与修改

1.直接访问图像像素（索引法）

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL2);
 
#include <vtkSmartPointer.h>
#include <vtkImageData.h>
#include <vtkBMPReader.h>
#include <vtkImageViewer2.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
 
int main()
{
  vtkSmartPointer<vtkBMPReader> reader =
    vtkSmartPointer<vtkBMPReader>::New();
  reader->SetFileName("lena.bmp");
  reader->Update();
 
  int dims[3];
  reader->GetOutput()->GetDimensions(dims);
 
  int nbofComp;
  nbofComp = reader->GetOutput()->GetNumberOfScalarComponents();
 
  for (int k = 0; k < dims[2]; k++)
  {
    for (int j = 0; j < dims[1]; j++)
    {
      for (int i = 0; i < dims[0]; i++)
      {
        if (i < 384 && i > 128 && j > 128 && j < 384)
        {
           unsigned char *pixel = (unsigned char *)(reader->GetOutput()->GetScalarPointer(i, j, k));
        *pixel = 255 - *pixel;
        *(pixel + 1) = 255 - *(pixel + 1);
        *(pixel + 2) = 255 - *(pixel + 2);
        }
      }
    }
  }
 
  vtkSmartPointer<vtkImageViewer2> imgViewer =
    vtkSmartPointer<vtkImageViewer2>::New();
  imgViewer->SetInputData(reader->GetOutput());
 
  vtkSmartPointer<vtkRenderWindowInteractor> rwi =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  imgViewer->SetupInteractor(rwi);
  imgViewer->Render();
  imgViewer->GetRenderer()->ResetCamera();
  imgViewer->Render();
  imgViewer->GetRenderer()->SetBackground(1.0, 1.0, 1.0);
  imgViewer->SetSize(640, 480);
  imgViewer->GetRenderWindow()->SetWindowName("VisitImagePixelDirectly");
 
  rwi->Start();
 
  return 0;
}

 输出结果：

 2.迭代器方法访问图像像素

另外VTK中提供了vtkImageIterator类来利用迭代器方法访问图像像素。该类是一个模板类，使用时，需要提供迭代的图像像素类型以及迭代的区域大小。

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL2);
 
#include <vtkSmartPointer.h>
#include <vtkBMPReader.h>
#include <vtkImageData.h>
#include <vtkImageIterator.h>
#include <vtkImageViewer2.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
 
int main()
{
  vtkSmartPointer<vtkBMPReader> reader =
    vtkSmartPointer<vtkBMPReader>::New();
  reader->SetFileName("lena.bmp");
  reader->Update();
 
  int subRegion[6] = { 64, 448, 64, 448, 0, 0 };
  vtkImageIterator<unsigned char> iter(reader->GetOutput(),subRegion);
 
  while (!iter.IsAtEnd())
  {
    unsigned char *inSI = iter.BeginSpan();
    unsigned char *inSIEnd = iter.EndSpan();
 
    while ( inSI != inSIEnd )
    {
      *inSI = 255 - *inSI;
      ++inSI;
    }
    iter.NextSpan();
  }
 
  vtkSmartPointer<vtkImageViewer2> imgViewer =
    vtkSmartPointer<vtkImageViewer2>::New();
  imgViewer->SetInputConnection(reader->GetOutputPort());
 
  vtkSmartPointer<vtkRenderWindowInteractor> rwi =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  imgViewer->SetupInteractor(rwi);
  imgViewer->Render();
  imgViewer->GetRenderer()->ResetCamera();
  imgViewer->Render();
  imgViewer->GetRenderer()->SetBackground(1.0, 1.0, 1.0);
  imgViewer->SetSize(640, 480);
  imgViewer->GetRenderWindow()->SetWindowName("VisitImagePixelIteratively");
 
  rwi->Start();
 
  return 0;
}

输出结果：