ImageMagnify
VTKExamples/Cxx/Images/ImageMagnify
Description vtkImageMagnify increases the dimensions of an image by integral magnification factors. It also adjusts the spacing of the pixels so that the magnified image covers the same region as the original image. To stretch the image, the pixel spacing needs to be adjusted. This example uses vtkImageChangeInformation to modify the magnified image's spacing. The result is an image that has increased numbers of pixels and is stretched in the magnified directions.¶
Code¶
ImageMagnify.cxx
#include <vtkImageActor.h> #include <vtkInteractorStyleImage.h> #include <vtkImageData.h> #include <vtkImageMapper3D.h> #include <vtkRenderer.h> #include <vtkRenderWindow.h> #include <vtkRenderWindowInteractor.h> #include <vtkSmartPointer.h> #include <vtkPNGReader.h> #include <vtkImageMagnify.h> #include <vtkImageChangeInformation.h> int main(int argc, char *argv[]) { // Handle the arguments if(argc < 2) { std::cout << "Required arguments: filename.png" << std::endl; return EXIT_FAILURE; } // Read the image vtkSmartPointer<vtkPNGReader> reader = vtkSmartPointer<vtkPNGReader>::New(); reader->SetFileName(argv[1]); // Increase the dimensions of the image vtkSmartPointer<vtkImageMagnify> magnifyFilter = vtkSmartPointer<vtkImageMagnify>::New(); magnifyFilter->SetInputConnection(reader->GetOutputPort()); magnifyFilter->SetMagnificationFactors(2,1,1); magnifyFilter->Update(); // Adjust the spacing of the magnified image. This will stretch the // image vtkSmartPointer<vtkImageChangeInformation> changeFilter = vtkSmartPointer<vtkImageChangeInformation>::New(); changeFilter->SetInputConnection(magnifyFilter->GetOutputPort()); changeFilter->SetSpacingScale( magnifyFilter->GetMagnificationFactors()[0], magnifyFilter->GetMagnificationFactors()[1], magnifyFilter->GetMagnificationFactors()[2]); vtkSmartPointer<vtkImageActor> originalActor = vtkSmartPointer<vtkImageActor>::New(); originalActor->GetMapper()->SetInputConnection( reader->GetOutputPort()); vtkSmartPointer<vtkImageActor> magnifiedActor = vtkSmartPointer<vtkImageActor>::New(); magnifiedActor->GetMapper()->SetInputConnection( changeFilter->GetOutputPort()); // Define viewport ranges // (xmin, ymin, xmax, ymax) double originalViewport[4] = {0.0, 0.0, 0.5, 1.0}; double magnifiedViewport[4] = {0.5, 0.0, 1.0, 1.0}; // Setup renderers vtkSmartPointer<vtkRenderer> originalRenderer = vtkSmartPointer<vtkRenderer>::New(); originalRenderer->SetViewport(originalViewport); originalRenderer->AddActor(originalActor); originalRenderer->ResetCamera(); originalRenderer->SetBackground(.4, .5, .6); vtkSmartPointer<vtkRenderer> magnifiedRenderer = vtkSmartPointer<vtkRenderer>::New(); magnifiedRenderer->SetViewport(magnifiedViewport); magnifiedRenderer->AddActor(magnifiedActor); magnifiedRenderer->ResetCamera(); magnifiedRenderer->SetBackground(.4, .5, .7); vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New(); renderWindow->SetSize(600, 300); renderWindow->AddRenderer(originalRenderer); renderWindow->AddRenderer(magnifiedRenderer); vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New(); vtkSmartPointer<vtkInteractorStyleImage> style = vtkSmartPointer<vtkInteractorStyleImage>::New(); renderWindowInteractor->SetInteractorStyle(style); renderWindowInteractor->SetRenderWindow(renderWindow); renderWindow->Render(); renderWindowInteractor->Initialize(); renderWindowInteractor->Start(); return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.3 FATAL_ERROR) project(ImageMagnify) find_package(VTK COMPONENTS vtkCommonCore vtkCommonDataModel vtkIOImage vtkImagingCore vtkInteractionStyle vtkRenderingContextOpenGL2 vtkRenderingCore vtkRenderingFreeType vtkRenderingGL2PSOpenGL2 vtkRenderingOpenGL2 QUIET) if (NOT VTK_FOUND) message("Skipping ImageMagnify: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION: ${VTK_VERSION}") if (VTK_VERSION VERSION_LESS "8.90.0") # old system include(${VTK_USE_FILE}) add_executable(ImageMagnify MACOSX_BUNDLE ImageMagnify.cxx ) target_link_libraries(ImageMagnify PRIVATE ${VTK_LIBRARIES}) else () # include all components add_executable(ImageMagnify MACOSX_BUNDLE ImageMagnify.cxx ) target_link_libraries(ImageMagnify PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS ImageMagnify MODULES ${VTK_LIBRARIES} ) endif ()
Download and Build ImageMagnify¶
Click here to download ImageMagnify and its CMakeLists.txt file. Once the tarball ImageMagnify.tar has been downloaded and extracted,
cd ImageMagnify/build
If VTK is installed:
cmake ..
If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..
Build the project:
make
and run it:
./ImageMagnify
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.