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| <div class="floatcenter">[[File:ITK_Examples_Baseline_EdgesAndGradients_TestZeroCrossingBasedEdgeDetectionImageFilter.png]]</div>
| | {{warning|1=The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/* pages likely require ITK version 4.13 or earlier releases. In many cases, the examples on this page no longer conform to the best practices for modern ITK versions.}} |
| The zero-crossing based edge detector looks for pixels in the Laplacian of | |
| an image where the value of the Laplacian passes through zero --- points
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| where the Laplacian changes sign. Such points often occur at ``edges'' in
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| images --- i.e. points where the intensity of the image changes rapidly,
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| but they also occur at places that are not as easy to associate with edges.
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| This example requires an input file and an optional variance.
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| Contributed by: Bill Lorensen
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| ==ZeroCrossingBasedEdgeDetectionImageFilter.cxx==
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| <source lang="cpp">
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| #include "itkImage.h"
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| #include "itkImageFileReader.h"
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| #include "itkImageFileWriter.h"
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| #include "itkZeroCrossingBasedEdgeDetectionImageFilter.h"
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| #include "itksys/SystemTools.hxx"
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| #include "QuickView.h"
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| int main(int argc, char * argv[])
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| {
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| // Verify command line arguments
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| if( argc < 2 )
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| {
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| std::cerr << "Usage: " << std::endl;
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| std::cerr << argv[0] << " inputImageFile" << std::endl;
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| return EXIT_FAILURE;
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| }
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| double var = 5.0;
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| if (argc > 2)
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| {
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| var = atof(argv[2]);
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| }
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| // Parse command line arguments
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| std::string inputFilename = argv[1];
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| // Setup types
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| typedef itk::Image< float, 2 > FloatImageType;
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| typedef itk::ImageFileReader< FloatImageType > ReaderType;
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| typedef itk::ZeroCrossingBasedEdgeDetectionImageFilter<
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| FloatImageType, FloatImageType > FilterType;
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| // Create and setup a reader
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| ReaderType::Pointer reader = ReaderType::New();
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| reader->SetFileName( inputFilename.c_str() );
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| // Create and setup a derivative filter
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| FilterType::Pointer edgeDetector = FilterType::New();
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| edgeDetector->SetInput( reader->GetOutput() );
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| FilterType::ArrayType variance;
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| variance.Fill(var);
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| edgeDetector->SetVariance(variance);
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| QuickView viewer;
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| viewer.AddImage(
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| reader->GetOutput(),true,
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| itksys::SystemTools::GetFilenameName(inputFilename));
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| std::stringstream desc;
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| desc << "ZeroBasedEdgeDetection, variance = " | |
| << edgeDetector->GetVariance();
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| viewer.AddImage(
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| edgeDetector->GetOutput(),
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| true,
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| desc.str());
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| viewer.Visualize();
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| return EXIT_SUCCESS;
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| }
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| </source>
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| {{ITKVTKCMakeLists|{{SUBPAGENAME}}}}
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