VTK 求灰度图和直方图

实现效果：

 

 

代码如下：

    double leftview[4] = {0,0, 0.33,1};
    double midview[4] = {0.33,0, 0.66,1};
    double rightview[4] = {0.66,0, 1.0,1};
    int bins = 256;
    int comps = 1;

    vtkSmartPointer<vtkJPEGReader> reader = vtkSmartPointer<vtkJPEGReader>::New();
    reader->SetFileName("d:/lena.jpg");
    reader->Update();
    vtkSmartPointer<vtkImageActor> actor1 = vtkSmartPointer<vtkImageActor>::New();
    actor1->GetMapper()->SetInputConnection(reader->GetOutputPort());
    vtkSmartPointer<vtkRenderer> render1 = vtkSmartPointer<vtkRenderer>::New();
    render1->AddActor(actor1);
    render1->SetViewport(leftview);
    render1->ResetCamera();
    render1->SetBackground(0,1,0);

    vtkSmartPointer<vtkImageLuminance> lum = vtkSmartPointer<vtkImageLuminance>::New();
    lum->SetInputConnection(reader->GetOutputPort());
    lum->Update();
    vtkSmartPointer<vtkImageActor> actorgray = vtkSmartPointer<vtkImageActor>::New();
    actorgray->GetMapper()->SetInputConnection(lum->GetOutputPort());
    vtkSmartPointer<vtkRenderer> rendergray = vtkSmartPointer<vtkRenderer>::New();
    rendergray->AddActor(actorgray);
    rendergray->SetViewport(midview);
    rendergray->ResetCamera();
    rendergray->SetBackground(1,0,0);

    vtkSmartPointer<vtkImageAccumulate> his = vtkSmartPointer<vtkImageAccumulate>::New();
    his->SetInputData(lum->GetOutput());
    his->SetComponentExtent(0, bins-1, 0,0,0,0);
    his->SetComponentOrigin(0,0,0);
    his->SetComponentSpacing(256.0/bins, 0,0);
    his->Update();
    vtkSmartPointer<vtkIntArray> freq = vtkSmartPointer<vtkIntArray>::New();
    freq->SetNumberOfComponents(1);
    int *output = static_cast<int*>(his->GetOutput()->GetScalarPointer());
    for(int j=0; j < bins; j++){
        for(int i=0; i < comps; i++){
            freq->InsertNextTuple1(*output);
            output++;
        }
    }
    vtkSmartPointer<vtkDataObject> dobj = vtkSmartPointer<vtkDataObject>::New();
    dobj->GetFieldData()->AddArray(freq);
    vtkSmartPointer<vtkBarChartActor> actor2=vtkSmartPointer<vtkBarChartActor>::New();
    actor2->SetInput(dobj);
    actor2->SetTitle("histogram");
    actor2->GetProperty()->SetColor(1,1,1);
    actor2->GetLegendActor()->SetNumberOfEntries(dobj->GetFieldData()->GetArray(0)->GetNumberOfTuples());
    actor2->LegendVisibilityOff();
    actor2->LabelVisibilityOff();
    double colors[3][3] = {{1,0,0},{0,1,0},{0,0,1}};
    for(int i =0;i < bins; i++){
        actor2->SetBarColor(i, colors[0]);
    }
    vtkSmartPointer<vtkRenderer> render2 = vtkSmartPointer<vtkRenderer>::New();
    render2->AddActor(actor2);
    render2->SetViewport(rightview);
    render2->ResetCamera();
    render2->SetBackground(0,0,1);

    pRenderWindow->AddRenderer(render1);
    pRenderWindow->AddRenderer(rendergray);
    pRenderWindow->AddRenderer(render2);