1、使用 vtkImageMask  实现。

优点：简单方便，mask与原始图像大小一致；

缺点：只支持单一掩码图像，无法实现多个掩码的编辑；

2、演示源码

void ImageMask2()
{
   // 读取数据
	int m_Dim[3] = { 512,512,333 };
	double m_Spacing[3] = { 0.32,0.32,0.8 };

	double m_Origin[3];

	m_Origin[0] = -m_Dim[0] * m_Spacing[0] * 0.5;
	m_Origin[1] = -m_Dim[1] * m_Spacing[1] * 0.5;
	m_Origin[2] = -m_Dim[2] * m_Spacing[2] * 0.5;

	size_t fSize = m_Dim[0] * m_Dim[1] * m_Dim[2] * sizeof(short);

	vtkImageData* input = vtkImageData::New();
	input->SetDimensions(m_Dim[0], m_Dim[1], m_Dim[2]);
	input->SetSpacing(m_Spacing[0], m_Spacing[1], m_Spacing[2]);
	input->SetOrigin(m_Origin);
	input->AllocateScalars(VTK_SHORT, 1);
	void *ptr = input->GetScalarPointer();
	//memcpy(ptr, m_pSrcData->m_pSrc, fSize);

	std::string m_ImgFile = "D:\\spineCT\\IMG-0001-00001.img";
	FILE *pFile = fopen(m_ImgFile.c_str(), "rb");
	if (pFile == NULL)
		return;

	fread(ptr, 1, fSize, pFile);
	fclose(pFile);


	//====================================================
    // 创建测试掩码图像
	vtkImageData* mask = vtkImageData::New();
	mask->SetDimensions(m_Dim[0], m_Dim[1], m_Dim[2]);
	mask->SetSpacing(m_Spacing[0], m_Spacing[1], m_Spacing[2]);
	mask->SetOrigin(m_Origin);
	mask->AllocateScalars(VTK_UNSIGNED_CHAR, 1);
	void *ptrMak = mask->GetScalarPointer();
	memset(ptrMak, 0, 512 * 512 * 333);

	unsigned char* pMask = (unsigned char*)ptrMak;
	for (int i = 0; i < 333; i++)
	{
		for (int j = 200; j < 400; j++)
		{
			for (int k = 200; k < 400; k++)
			{
				pMask[i * 512 * 512 + j * 512 + k] = 255;
			}

		}
	}
	//====================================================

	vtkSmartPointer<vtkImageMapToWindowLevelColors> windowLevel = vtkSmartPointer<vtkImageMapToWindowLevelColors>::New();
	
	windowLevel->SetWindow(800);
	windowLevel->SetLevel(800);
	windowLevel->SetInputData(input);
	windowLevel->Update();


	vtkNew<vtkImageMask> maskFilter;
	maskFilter->SetImageInputData(windowLevel->GetOutput());
	maskFilter->SetMaskInputData(mask);

	maskFilter->SetMaskedOutputValue(255, 0, 0);
	maskFilter->SetMaskAlpha(0.4);
	maskFilter->NotMaskOn();  // 255 不可见
	maskFilter->Update();


	int imeExtent[6];
	input->GetExtent(imeExtent);
	input->GetExtent(ImageExtent);

	imeExtent[4] = 0;
	imeExtent[5] = 0;
	// Display the image
	vtkSmartPointer<vtkImageActor> actor = vtkSmartPointer<vtkImageActor>::New();
	actor->GetMapper()->SetInputConnection(maskFilter->GetOutputPort());
	actor->SetDisplayExtent(imeExtent);


	//itemActor->SetOrigin();
	vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
	renderer->AddActor(actor);

	vtkCamera* camera  = renderer->GetActiveCamera();
	camera->ParallelProjectionOn();
	camera->SetParallelScale(100);
	camera->SetFocalPoint(0,0,0);
	camera->SetPosition(0,0,400);
	camera->SetViewUp(0,1,0);

	vtkSmartPointer<vtkRenderWindow> window = vtkSmartPointer<vtkRenderWindow>::New();
	window->AddRenderer(renderer);

	// Set up the interaction
	vtkSmartPointer<vtkInteractorStyleImage> imageStyle = vtkSmartPointer<vtkInteractorStyleImage>::New();
	vtkSmartPointer<vtkRenderWindowInteractor> interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
	interactor->SetInteractorStyle(imageStyle);
	window->SetInteractor(interactor);
	window->Render();

	vtkSmartPointer<vtkImageInteractionCallback> callback = vtkSmartPointer<vtkImageInteractionCallback>::New();
	callback->SetImageReslice(actor, itemActor, renderer);
	callback->SetInteractor(interactor);

	imageStyle->AddObserver(vtkCommand::MouseMoveEvent, callback);
	imageStyle->AddObserver(vtkCommand::LeftButtonPressEvent, callback);
	imageStyle->AddObserver(vtkCommand::LeftButtonReleaseEvent, callback);

	imageStyle->AddObserver(vtkCommand::KeyPressEvent, callback);


	// Start interaction
	// The Start() method doesn't return until the window is closed by the user
	interactor->Start();
}

3、勾画交互-矩形工具

4、勾画交互-圆形工具