1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190
|
/*=========================================================================
*
* Copyright Insight Software Consortium
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
// Software Guide : BeginLatex
//
// This example introduces the use of the
// \doxygen{CannyEdgeDetectionImageFilter}. Canny edge detection is widely used for
// edge detection since it is the optimal solution satisfying the constraints
// of good sensitivity, localization and noise robustness. To achieve this
// end, Canny edge detection is implemented internally as a multi-stage
// algorithm, which involves Gaussian smoothing to remove noise, calculation
// of gradient magnitudes to localize edge features, non-maximum suppression
// to remove suprious features, and finally thresholding to yield a binary image.
// Though the specifics of this internal pipeline are largely abstracted from
// the user of the class, it is nonetheless beneficial to have a general
// understanding of these components so that parameters can be appropriately
// adjusted.
//
// \index{itk::CannyEdgeDetectionImageFilter|textbf}
//
// The first step required for using this filter is to include its header file.
//
// \index{itk::CannyEdgeDetectionImageFilter!header}
//
// Software Guide : EndLatex
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkCastImageFilter.h"
#include "itkRescaleIntensityImageFilter.h"
// Software Guide : BeginCodeSnippet
#include "itkCannyEdgeDetectionImageFilter.h"
// Software Guide : EndCodeSnippet
int main(int argc, char* argv[])
{
if( argc < 3 )
{
std::cerr << "Usage: " << std::endl;
std::cerr << argv[0]
<< " inputImage outputImage"
<< " [variance upperThreshold lowerThreshold]" << std::endl;
return EXIT_FAILURE;
}
const char * inputFilename = argv[1];
const char * outputFilename = argv[2];
float variance = 2.0;
float upperThreshold = 0.0;
float lowerThreshold = 0.0;
if( argc > 3 )
{
variance = atof( argv[3] );
}
if( argc > 4 )
{
upperThreshold = atof( argv[4] );
}
if( argc > 5 )
{
lowerThreshold = atof( argv[5] );
}
std::cout << "Variance = " << variance << std::endl;
std::cout << "UpperThreshold = " << upperThreshold << std::endl;
std::cout << "LowerThreshold = " << lowerThreshold << std::endl;
// Software Guide : BeginLatex
//
// In this example, images are read and written with \code{unsigned char}
// pixel type. However, Canny edge detection requires floating point
// pixel types in order to avoid numerical errors. For this reason,
// a separate internal image type with pixel type \code{double} is defined
// for edge detection.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
const unsigned int Dimension = 2;
typedef unsigned char CharPixelType; // IO
typedef double RealPixelType; // Operations
typedef itk::Image< CharPixelType, Dimension > CharImageType;
typedef itk::Image< RealPixelType, Dimension > RealImageType;
// Software Guide : EndCodeSnippet
typedef itk::ImageFileReader< CharImageType > ReaderType;
typedef itk::ImageFileWriter< CharImageType > WriterType;
// Software Guide : BeginLatex
//
// The \code{CharImageType} image is cast to and from \code{RealImageType}
// using \doxygen{CastImageFilter} and \code{RescaleIntensityImageFilter},
// respectively; both the input and output of \code{CannyEdgeDetectionImageFilter}
// are \code{RealImageType}.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
typedef itk::CastImageFilter< CharImageType, RealImageType >
CastToRealFilterType;
typedef itk::CannyEdgeDetectionImageFilter< RealImageType, RealImageType >
CannyFilterType;
typedef itk::RescaleIntensityImageFilter< RealImageType, CharImageType >
RescaleFilterType;
// Software Guide : EndCodeSnippet
//Setting the IO
ReaderType::Pointer reader = ReaderType::New();
CastToRealFilterType::Pointer toReal = CastToRealFilterType::New();
CannyFilterType::Pointer cannyFilter = CannyFilterType::New();
RescaleFilterType::Pointer rescale = RescaleFilterType::New();
WriterType::Pointer writer = WriterType::New();
reader->SetFileName( inputFilename );
writer->SetFileName( outputFilename );
toReal->SetInput( reader->GetOutput() );
cannyFilter->SetInput( toReal->GetOutput() );
rescale->SetInput( cannyFilter->GetOutput() );
writer->SetInput( rescale->GetOutput() );
// Software Guide : BeginLatex
//
// In this example, three parameters of the Canny edge detection
// filter may be set via the \code{SetVariance()}, \code{SetUpperThreshold()},
// and \code{SetLowerThreshold()} methods. Based on the previous discussion
// of the steps in the internal pipeline, we understand that
// \code{variance} adjusts the amount of Gaussian smoothing and
// \code{upperThreshold} and \code{lowerThreshold} control which edges are
// selected in the final step.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
cannyFilter->SetVariance( variance );
cannyFilter->SetUpperThreshold( upperThreshold );
cannyFilter->SetLowerThreshold( lowerThreshold );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally, \code{Update()} is called on \code{writer} to trigger excecution
// of the pipeline. As usual, the call is wrapped in a \code{try/catch}
// block.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch( itk::ExceptionObject & err )
{
std::cout << "ExceptionObject caught !" << std::endl;
std::cout << err << std::endl;
return EXIT_FAILURE;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}
|