Difference between revisions of "VTK/Examples/Cxx/Images/ImageLuminance"

From KitwarePublic
< VTK‎ | Examples‎ | Cxx
Jump to navigationJump to search
(added visualization)
(→‎ImageLuminance.cxx: simplify / sync w/ ImageMagnitude example)
 
(7 intermediate revisions by 3 users not shown)
Line 1: Line 1:
 +
<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 <vtkJPEGWriter.h>
+
#include <vtkImageMapper3D.h>
 
#include <vtkImageCanvasSource2D.h>
 
#include <vtkImageCanvasSource2D.h>
 
#include <vtkImageLuminance.h>
 
#include <vtkImageLuminance.h>
Line 12: Line 20:
 
#include <vtkJPEGReader.h>
 
#include <vtkJPEGReader.h>
 
#include <vtkImageActor.h>
 
#include <vtkImageActor.h>
#include <vtkImageEllipsoidSource.h>
 
#include <vtkImageCast.h>
 
  
 
int main(int, char *[])
 
int main(int, char *[])
Line 41: Line 47:
 
   vtkSmartPointer<vtkImageActor> originalActor =
 
   vtkSmartPointer<vtkImageActor> originalActor =
 
     vtkSmartPointer<vtkImageActor>::New();
 
     vtkSmartPointer<vtkImageActor>::New();
   originalActor->SetInput(source->GetOutput());
+
   originalActor->GetMapper()->SetInputConnection(
 +
    source->GetOutputPort());
  
 
   vtkSmartPointer<vtkImageActor> luminanceActor =
 
   vtkSmartPointer<vtkImageActor> luminanceActor =
 
     vtkSmartPointer<vtkImageActor>::New();
 
     vtkSmartPointer<vtkImageActor>::New();
   luminanceActor->SetInput(luminanceFilter->GetOutput());
+
   luminanceActor->GetMapper()->SetInputConnection(
 +
    luminanceFilter->GetOutputPort());
  
 
   // Define viewport ranges
 
   // Define viewport ranges
Line 84: Line 92:
  
 
   renderWindowInteractor->Start();
 
   renderWindowInteractor->Start();
 +
 
   return EXIT_SUCCESS;
 
   return EXIT_SUCCESS;
 
}
 
}
 
</source>
 
 
==CMakeLists.txt==
 
<source lang="cmake">
 
cmake_minimum_required(VERSION 2.6)
 
PROJECT(ImageLuminance)
 
 
FIND_PACKAGE(VTK REQUIRED)
 
INCLUDE(${VTK_USE_FILE})
 
 
ADD_EXECUTABLE(ImageLuminance ImageLuminance.cxx)
 
TARGET_LINK_LIBRARIES(ImageLuminance vtkHybrid)
 
 
 
</source>
 
</source>
  
[[Category:VTKAddVisualization]]
+
{{VTKCMakeLists|{{SUBPAGENAME}}}}

Latest revision as of 12:28, 8 January 2016

VTK Examples Baseline Images TestImageLuminance.png

There are two ways to convert images to greyscale:

For an example of usage of the vtkImageMagnitude filter, see VTK/Examples/Cxx/Images/ImageMagnitude.

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.