VTK 实例25：BMP图像像素值的访问与修改

#include "vtkAutoInit.h" 
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkInteractionStyle);
#include <vtkSmartPointer.h>
#include <vtkImageViewer2.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkBMPReader.h>
#include <vtkImageData.h>
#include <vtkImageIterator.h>

//测试图像：../data/lena.bmp
int main(int argc, char* argv[])
{
    vtkSmartPointer<vtkBMPReader> reader =
    vtkSmartPointer<vtkBMPReader>::New();
    reader->SetFileName ( "lena.bmp" );
    reader->Update();

    int subRegion[6] = {0,300, 0, 300, 0, 0};
    vtkImageIterator<unsigned char> it(reader->GetOutput(), subRegion);

    while(!it.IsAtEnd())
    {
        unsigned char *inSI = it.BeginSpan();
        unsigned char *inSIEnd = it.EndSpan();

        while(inSI != inSIEnd)
        {
            *inSI = 255-*inSI;
            ++inSI;
        }
        it.NextSpan();
    }

    vtkSmartPointer<vtkImageViewer2> imageViewer =
        vtkSmartPointer<vtkImageViewer2>::New();
    imageViewer->SetInputConnection(reader->GetOutputPort());

    vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
    imageViewer->SetupInteractor(renderWindowInteractor);
    imageViewer->Render();
    imageViewer->GetRenderer()->ResetCamera();
    imageViewer->Render();

    imageViewer->GetRenderer()->SetBackground(1.0, 1.0, 1.0);
    imageViewer->SetSize(640, 480);
    imageViewer->GetRenderWindow()->SetWindowName("VisitImagePixelIterativelyExample");

    renderWindowInteractor->Start();

    return 0;
}