Difference between revisions of "VTK/Examples/Cxx/Images/ImageLuminance"
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+ | <div class="floatright">[[File:VTK_Examples_Baseline_Images_TestImageLuminance.png|400px]]</div> | ||
+ | |||
+ | There are two ways to convert images to greyscale: | ||
+ | * {{class|vtkImageLuminance}} uses the [[wikipedia:Luma (video)|luminance equation]] for properly weighting the R, G, and B components; | ||
+ | * {{class|vtkImageMagnitude}} does a simple sum-of-squares computation of the components (i.e. the [[wikipedia:Magnitude (mathematics)#Euclidean vector space|Euclidean norm]] -- not the [[wikipedia:Root mean square|quadratic mean]]!), and is meant for vector data. | ||
+ | |||
+ | For an example of usage of the vtkImageMagnitude filter, see [[../ImageMagnitude]]. | ||
+ | |||
==ImageLuminance.cxx== | ==ImageLuminance.cxx== | ||
<source lang="cpp"> | <source lang="cpp"> | ||
#include <vtkSmartPointer.h> | #include <vtkSmartPointer.h> | ||
#include <vtkImageData.h> | #include <vtkImageData.h> | ||
− | #include < | + | #include <vtkImageMapper3D.h> |
#include <vtkImageCanvasSource2D.h> | #include <vtkImageCanvasSource2D.h> | ||
#include <vtkImageLuminance.h> | #include <vtkImageLuminance.h> | ||
+ | #include <vtkRenderWindow.h> | ||
+ | #include <vtkRenderWindowInteractor.h> | ||
+ | #include <vtkInteractorStyleImage.h> | ||
+ | #include <vtkRenderer.h> | ||
+ | #include <vtkJPEGReader.h> | ||
+ | #include <vtkImageActor.h> | ||
int main(int, char *[]) | int main(int, char *[]) | ||
{ | { | ||
− | // | + | // Create an image of a rectangle |
− | vtkSmartPointer<vtkImageCanvasSource2D> source = | + | vtkSmartPointer<vtkImageCanvasSource2D> source = |
− | + | vtkSmartPointer<vtkImageCanvasSource2D>::New(); | |
source->SetScalarTypeToUnsignedChar(); | source->SetScalarTypeToUnsignedChar(); | ||
source->SetNumberOfScalarComponents(3); | source->SetNumberOfScalarComponents(3); | ||
source->SetExtent(0, 200, 0, 200, 0, 0); | source->SetExtent(0, 200, 0, 200, 0, 0); | ||
− | + | ||
− | // | + | // Clear the image |
source->SetDrawColor(0,0,0); | source->SetDrawColor(0,0,0); | ||
source->FillBox(0,200,0,200); | source->FillBox(0,200,0,200); | ||
− | + | ||
− | // | + | // Draw a red box |
source->SetDrawColor(255,0,0); | source->SetDrawColor(255,0,0); | ||
source->FillBox(100,120,100,120); | source->FillBox(100,120,100,120); | ||
source->Update(); | source->Update(); | ||
− | + | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
vtkSmartPointer<vtkImageLuminance> luminanceFilter = | vtkSmartPointer<vtkImageLuminance> luminanceFilter = | ||
vtkSmartPointer<vtkImageLuminance>::New(); | vtkSmartPointer<vtkImageLuminance>::New(); | ||
luminanceFilter->SetInputConnection(source->GetOutputPort()); | luminanceFilter->SetInputConnection(source->GetOutputPort()); | ||
luminanceFilter->Update(); | luminanceFilter->Update(); | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | </ | + | // Create actors |
+ | vtkSmartPointer<vtkImageActor> originalActor = | ||
+ | vtkSmartPointer<vtkImageActor>::New(); | ||
+ | originalActor->GetMapper()->SetInputConnection( | ||
+ | source->GetOutputPort()); | ||
+ | |||
+ | vtkSmartPointer<vtkImageActor> luminanceActor = | ||
+ | vtkSmartPointer<vtkImageActor>::New(); | ||
+ | luminanceActor->GetMapper()->SetInputConnection( | ||
+ | luminanceFilter->GetOutputPort()); | ||
+ | |||
+ | // Define viewport ranges | ||
+ | // (xmin, ymin, xmax, ymax) | ||
+ | double originalViewport[4] = {0.0, 0.0, 0.5, 1.0}; | ||
+ | double luminanceViewport[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> luminanceRenderer = | ||
+ | vtkSmartPointer<vtkRenderer>::New(); | ||
+ | luminanceRenderer->SetViewport(luminanceViewport); | ||
+ | luminanceRenderer->AddActor(luminanceActor); | ||
+ | luminanceRenderer->ResetCamera(); | ||
+ | luminanceRenderer->SetBackground(.4, .5, .7); | ||
+ | |||
+ | vtkSmartPointer<vtkRenderWindow> renderWindow = | ||
+ | vtkSmartPointer<vtkRenderWindow>::New(); | ||
+ | renderWindow->SetSize(600, 300); | ||
+ | renderWindow->AddRenderer(originalRenderer); | ||
+ | renderWindow->AddRenderer(luminanceRenderer); | ||
+ | |||
+ | vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = | ||
+ | vtkSmartPointer<vtkRenderWindowInteractor>::New(); | ||
+ | vtkSmartPointer<vtkInteractorStyleImage> style = | ||
+ | vtkSmartPointer<vtkInteractorStyleImage>::New(); | ||
− | + | renderWindowInteractor->SetInteractorStyle(style); | |
− | |||
− | |||
− | |||
− | + | renderWindowInteractor->SetRenderWindow(renderWindow); | |
− | + | renderWindowInteractor->Initialize(); | |
− | + | renderWindowInteractor->Start(); | |
− | |||
+ | return EXIT_SUCCESS; | ||
+ | } | ||
</source> | </source> | ||
+ | |||
+ | {{VTKCMakeLists|{{SUBPAGENAME}}}} |
Latest revision as of 12:28, 8 January 2016
There are two ways to convert images to greyscale:
- vtkImageLuminance uses the luminance equation for properly weighting the R, G, and B components;
- vtkImageMagnitude does a simple sum-of-squares computation of the components (i.e. the Euclidean norm -- not the quadratic mean!), and is meant for vector data.
For an example of usage of the vtkImageMagnitude filter, see VTK/Examples/Cxx/Images/ImageMagnitude.
Contents
ImageLuminance.cxx
#include <vtkSmartPointer.h>
#include <vtkImageData.h>
#include <vtkImageMapper3D.h>
#include <vtkImageCanvasSource2D.h>
#include <vtkImageLuminance.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleImage.h>
#include <vtkRenderer.h>
#include <vtkJPEGReader.h>
#include <vtkImageActor.h>
int main(int, char *[])
{
// Create an image of a rectangle
vtkSmartPointer<vtkImageCanvasSource2D> source =
vtkSmartPointer<vtkImageCanvasSource2D>::New();
source->SetScalarTypeToUnsignedChar();
source->SetNumberOfScalarComponents(3);
source->SetExtent(0, 200, 0, 200, 0, 0);
// Clear the image
source->SetDrawColor(0,0,0);
source->FillBox(0,200,0,200);
// Draw a red box
source->SetDrawColor(255,0,0);
source->FillBox(100,120,100,120);
source->Update();
vtkSmartPointer<vtkImageLuminance> luminanceFilter =
vtkSmartPointer<vtkImageLuminance>::New();
luminanceFilter->SetInputConnection(source->GetOutputPort());
luminanceFilter->Update();
// Create actors
vtkSmartPointer<vtkImageActor> originalActor =
vtkSmartPointer<vtkImageActor>::New();
originalActor->GetMapper()->SetInputConnection(
source->GetOutputPort());
vtkSmartPointer<vtkImageActor> luminanceActor =
vtkSmartPointer<vtkImageActor>::New();
luminanceActor->GetMapper()->SetInputConnection(
luminanceFilter->GetOutputPort());
// Define viewport ranges
// (xmin, ymin, xmax, ymax)
double originalViewport[4] = {0.0, 0.0, 0.5, 1.0};
double luminanceViewport[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> luminanceRenderer =
vtkSmartPointer<vtkRenderer>::New();
luminanceRenderer->SetViewport(luminanceViewport);
luminanceRenderer->AddActor(luminanceActor);
luminanceRenderer->ResetCamera();
luminanceRenderer->SetBackground(.4, .5, .7);
vtkSmartPointer<vtkRenderWindow> renderWindow =
vtkSmartPointer<vtkRenderWindow>::New();
renderWindow->SetSize(600, 300);
renderWindow->AddRenderer(originalRenderer);
renderWindow->AddRenderer(luminanceRenderer);
vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
vtkSmartPointer<vtkInteractorStyleImage> style =
vtkSmartPointer<vtkInteractorStyleImage>::New();
renderWindowInteractor->SetInteractorStyle(style);
renderWindowInteractor->SetRenderWindow(renderWindow);
renderWindowInteractor->Initialize();
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
Please try the new VTKExamples website.
CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
PROJECT(ImageLuminance)
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
add_executable(ImageLuminance MACOSX_BUNDLE ImageLuminance.cxx)
if(VTK_LIBRARIES)
target_link_libraries(ImageLuminance ${VTK_LIBRARIES})
else()
target_link_libraries(ImageLuminance vtkHybrid vtkWidgets)
endif()
Download and Build ImageLuminance
Click here to download ImageLuminance. and its CMakeLists.txt file.
Once the tarball ImageLuminance.tar has been downloaded and extracted,
cd ImageLuminance/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:
./ImageLuminance
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.