vtkImageBlend：处理一个窗口中显示多个图像（图像融合技术），接收多个图像输入，输出为融合图像。

注：此文知识学习笔记，仅记录完整程序和实现结果，具体原理参见：

https://blog.csdn.net/www_doling_net/article/details/8541534

#include <vtkAutoInit.h>  
VTK_MODULE_INIT(vtkRenderingOpenGL2);

#include <vtkSmartPointer.h>  
#include <vtkJPEGReader.h>  
//#include <vtkImageCast.h>  
#include <vtkImageData.h>  
#include <vtkImageCanvasSource2D.h>  
#include <vtkImageBlend.h>  
#include <vtkImageActor.h>  
#include <vtkRenderer.h>  
#include <vtkRenderWindow.h>  
#include <vtkRenderWindowInteractor.h>  
#include <vtkInteractorStyleImage.h>  

int main()
{
	//数据管线  
	vtkSmartPointer<vtkJPEGReader> reader = vtkSmartPointer<vtkJPEGReader>::New();
	reader->SetFileName("data/lena-gray.jpg");
	reader->Update();

	vtkSmartPointer<vtkImageCanvasSource2D> source = vtkSmartPointer<vtkImageCanvasSource2D>::New();
	source->SetNumberOfScalarComponents(1);
	source->SetScalarTypeToUnsignedChar();
	source->SetExtent(0, 512, 0, 512, 0, 0);
	source->SetDrawColor(0, 0, 0);
	source->FillBox(0, 512, 0, 512);
	source->SetDrawColor(255, 255, 255);
	source->FillBox(100, 400, 100, 400);
	source->Update();

	vtkSmartPointer<vtkImageBlend> blend = vtkSmartPointer<vtkImageBlend>::New();
	blend->AddInputData( reader->GetOutput());    //书中这里是SetInputData, 0，1 index删掉
	blend->AddInputData( source->GetOutput());    //
	blend->SetOpacity(0, 0.4);
	blend->SetOpacity(1, 0.6);
	blend->Update();

	//渲染引擎  
	vtkSmartPointer<vtkImageActor> actor1 = vtkSmartPointer<vtkImageActor>::New();
	actor1->SetInputData(reader->GetOutput());

	vtkSmartPointer<vtkImageActor> actor2 = vtkSmartPointer<vtkImageActor>::New();
	actor2->SetInputData(source->GetOutput());

	vtkSmartPointer<vtkImageActor> blend_actor = vtkSmartPointer<vtkImageActor>::New();
	blend_actor->SetInputData(blend->GetOutput());
	//定义视窗大小(xmin.ymin,xmax,ymax)  
	//按window的尺寸进行比例分割  
	double leftViewport[4] = { 0, 0, 0.33, 1 };
	double midViewport[4] = { 0.33, 0, 0.66, 1 };
	double rightViewport[4] = { 0.66, 0, 1, 1 };
	//render  
	vtkSmartPointer<vtkRenderer> render1 = vtkSmartPointer<vtkRenderer>::New();
	render1->SetViewport(leftViewport);
	render1->AddActor(actor1);
	render1->ResetCamera();
	render1->SetBackground(1, 1, 1);

	vtkSmartPointer<vtkRenderer> render2 = vtkSmartPointer<vtkRenderer>::New();
	render2->SetViewport(midViewport);
	render2->AddActor(actor2);
	render2->ResetCamera();
	render2->SetBackground(1, 1, 1);

	vtkSmartPointer<vtkRenderer> render3 = vtkSmartPointer<vtkRenderer>::New();
	render3->SetViewport(rightViewport);
	render3->AddActor(blend_actor);
	render3->ResetCamera();
	render3->SetBackground(1, 1, 1);
	//window  
	vtkSmartPointer<vtkRenderWindow> renderwindow = vtkSmartPointer<vtkRenderWindow>::New();
	renderwindow->AddRenderer(render1);
	renderwindow->AddRenderer(render2);
	renderwindow->AddRenderer(render3);
	renderwindow->SetSize(640, 320);
	renderwindow->SetWindowName("Image-Fusion");
	renderwindow->Render();
	//interactor  
	vtkSmartPointer<vtkRenderWindowInteractor> rwi = vtkSmartPointer<vtkRenderWindowInteractor>::New();
	vtkSmartPointer<vtkInteractorStyleImage> style = vtkSmartPointer<vtkInteractorStyleImage>::New();
	rwi->SetInteractorStyle(style);
	rwi->SetRenderWindow(renderwindow);
	rwi->Initialize();
	rwi->Start();

	return 0;
} 

运行结果：

参考资料：

1.《The Visualization Toolkit – AnObject-Oriented Approach To 3D Graphics (4th Edition)》
2. 张晓东, 罗火灵. VTK图形图像开发进阶[M]. 机械工业出版社, 2015.