VTK 图像基本操作_彩色图像生成灰度图像

1.灰度图像映射

vtkImageLuminance负责将一个RGB彩色图像转换为一个单组分的灰度图像。映射公式如下：

luminance = 0.3*R + 0.59*G + 0.11*B

该公式中，R为输入图像的第一分量（红色），G为第二分量（绿色），B为第三分量（蓝色）。这个计算结果计算一个RGB颜色的亮度。该类的使用也比较简单，用户无须设置参数，代码如下：

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL);
 
#include <vtkSmartPointer.h>
#include <vtkBMPReader.h>
#include <vtkImageLuminance.h>
#include <vtkImageActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleImage.h>
 
int main()
{
    vtkSmartPointer<vtkBMPReader> reader =
        vtkSmartPointer<vtkBMPReader>::New();
    reader->SetFileName("lena.bmp");
 
    vtkSmartPointer<vtkImageLuminance> luminanceFilter =
        vtkSmartPointer<vtkImageLuminance>::New();
    luminanceFilter->SetInputConnection(reader->GetOutputPort());
    luminanceFilter->Update();
    //原始演员
    vtkSmartPointer<vtkImageActor> origActor =
        vtkSmartPointer<vtkImageActor>::New();
    origActor->SetInputData(reader->GetOutput());
    //灰度演员
    vtkSmartPointer<vtkImageActor> shiftscaleActor =
        vtkSmartPointer<vtkImageActor>::New();
    shiftscaleActor->SetInputData(luminanceFilter->GetOutput());
    double origView[4] = { 0.0, 0.0, 0.5, 1.0 };
    double shiftscaleView[4] = { 0.5, 0.0, 1.0, 1.0 };
    //原始演员化妆
    vtkSmartPointer<vtkRenderer> origRender =
        vtkSmartPointer<vtkRenderer>::New();
    origRender->SetViewport(origView);
    origRender->AddActor(origActor);
    origRender->ResetCamera();
    origRender->SetBackground(1.0, 1.0, 1.0);
    //灰度演员化妆
    vtkSmartPointer<vtkRenderer> shiftscaleRender =
        vtkSmartPointer<vtkRenderer>::New();
    shiftscaleRender->SetViewport(shiftscaleView);
    shiftscaleRender->AddActor(shiftscaleActor);
    shiftscaleRender->ResetCamera();
    shiftscaleRender->SetBackground(1.0, 1.0, 1.0);
 
    vtkSmartPointer<vtkRenderWindow> renderwindow =
        vtkSmartPointer<vtkRenderWindow>::New();
    renderwindow->AddRenderer(origRender);
    renderwindow->AddRenderer(shiftscaleRender);
    renderwindow->SetSize(720, 480);
    renderwindow->Render();
    renderwindow->SetWindowName("RGB to Gray");
 
    vtkSmartPointer<vtkRenderWindowInteractor> rwi =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
    vtkSmartPointer<vtkInteractorStyleImage> style =
        vtkSmartPointer<vtkInteractorStyleImage>::New();
    rwi->SetInteractorStyle(style);
    rwi->SetRenderWindow(renderwindow);
    rwi->Initialize();
 
    rwi->Start();
    return 0;
}