1.各向异性扩散滤波
高斯平滑方法在平滑噪声的同时，模糊了图像重要的边缘图像。各向异性滤波是一种基于偏微分方程的滤波技术，建立于热量的各向异性扩散理论。各向异性滤波在图像的平坦区域选择大尺度平滑，而边缘区域则选择小尺度的平滑，在抑制噪声的同时保持了图像的边缘信息。
vtkImageAnisotropicDiffusion2D(vtkImageAnisotropicDiffusion3D)实现图像各向异性扩散滤波。
2.代码
#include "Test.h"#include <vtkAutoInit.h>VTK_MODULE_INIT(vtkRenderingOpenGL2);VTK_MODULE_INIT(vtkInteractionStyle);#include <vtkSmartPointer.h>#include <vtkJPEGReader.h>#include <vtkImageCast.h>#include <vtkImageAnisotropicDiffusion2D.h>#include <vtkImageActor.h>#include <vtkCamera.h>#include <vtkRenderer.h>#include <vtkRenderWindow.h>#include <vtkRenderWindowInteractor.h>#include <vtkInteractorStyleImage.h>int main(){vtkSmartPointer<vtkJPEGReader> reader =vtkSmartPointer<vtkJPEGReader>::New();reader->SetFileName("data/Lena.jpg");vtkSmartPointer<vtkImageAnisotropicDiffusion2D> diffusion =vtkSmartPointer<vtkImageAnisotropicDiffusion2D>::New();diffusion->SetInputConnection(reader->GetOutputPort());diffusion->SetNumberOfIterations(100);//SetNumberOfIterations()用于设置迭代的次数；vtkImageAnisotropicDiffusion2D通过迭代的方法实现；diffusion->SetDiffusionThreshold(5); //小于该阈值扩散 各向异性扩散滤波原理是在梯度较小的像素处进行较大幅度扩散，而在大梯度处则只进行细微的扩散diffusion->Update();//该类中还有一个梯度标志GradientMagnitudeThreshold，用来设置梯度算子。当该标志开时梯度通过中心差分方法计算；当标志为关时，需要单独处理每个相邻像素。//当像素与相邻像素梯度小于DiffusionThreshold时进行扩散处理.//创建角色vtkSmartPointer<vtkImageActor> originalActor =vtkSmartPointer<vtkImageActor>::New();originalActor->SetInputData(reader->GetOutput());vtkSmartPointer<vtkImageActor> diffusionActor =vtkSmartPointer<vtkImageActor>::New();diffusionActor->SetInputData(diffusion->GetOutput());double leftViewport[4] = {0.0, 0.0, 0.5, 1.0 };double rightViewport[4] = {0.5, 0.0, 1.0, 1.0 };vtkSmartPointer<vtkCamera> camera =vtkSmartPointer<vtkCamera>::New();vtkSmartPointer<vtkRenderer> leftRenderer =vtkSmartPointer<vtkRenderer>::New();leftRenderer->SetViewport(leftViewport);leftRenderer->AddActor(originalActor);leftRenderer->SetBackground(1.0, 0, 0);leftRenderer->SetActiveCamera(camera);leftRenderer->ResetCamera();vtkSmartPointer<vtkRenderer> rightRenderer =vtkSmartPointer<vtkRenderer>::New();rightRenderer->SetViewport(rightViewport);rightRenderer->SetBackground(1.0, 1.0, 1.0);rightRenderer->AddActor(diffusionActor);rightRenderer->SetActiveCamera(camera);//vtkSmartPointer<vtkRenderWindow> rw =vtkSmartPointer<vtkRenderWindow>::New();rw->AddRenderer(leftRenderer);rw->AddRenderer(rightRenderer);rw->SetSize(640, 320);rw->SetWindowName("Smooth by AnistropicFilter");vtkSmartPointer<vtkRenderWindowInteractor> rwi =vtkSmartPointer<vtkRenderWindowInteractor>::New();vtkSmartPointer<vtkInteractorStyleImage> style =vtkSmartPointer<vtkInteractorStyleImage>::New();rwi->SetInteractorStyle(style);rwi->SetRenderWindow(rw);rwi->Initialize();rwi->Start();return 0;}
3.运行截图
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