Segments structures in images based on image features derived from pseudo-canny-edges.
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Segments structures in images based on image features derived from pseudo-canny-edges.
- IMPORTANT
- The SegmentationLevelSetImageFilter class and the CannySegmentationLevelSetFunction class contain additional information necessary to the full understanding of how to use this filter.
- OVERVIEW
- This class is a level set method segmentation filter. It constructs a speed function which is designed to lock onto edges as detected by a Canny filter.
- The CannySegmentationLevelSetImageFilter can be a tool for refining an existing segmentation, or it can be used to try to segment a region by itself. Like all other level-set based segmentation filters (see SegmentationLevelSetImageFilter ), it works by first constructing a scalar speed term and a vector advection field based on edge features in the image. The level set front is then moved according to these two terms with the addition of a third curvature term to control the smoothness of the solution.
- The speed term is constructed as the Danielsson distance transform of the Canny edge image, as calculated by the CannyEdgeDetectionImageFilter . This scalar speed can be tuned in and out of the final evolution equation by setting the PropagationScaling parameter (a value of 0 removes the speed term).
- The advection field term is constructed by minimizing Danielsson distance squared. i.e. \( \mbox{min} \int D^2 \Rightarrow D \nabla D \) . This term moves the level set down the gradient of the distance transform.
- In practice, you may set the speed (propagation) term to zero if your initialization is already close to the edge you are interested in. If you are trying to segment a region by seeding with a small surface (blob, sphere) then you will likely want to add speed (propagation) to the equation so that the levelsets can expand along zero gradients. The relative influence of these two terms are controlled by the SetPropagationScaling and SetAdvectionScaling parameters.
- INPUTS
- This filter requires two inputs. The first input is a seed image. This seed image must contain an isosurface that you want to use as the seed for your segmentation. It can be a binary, graylevel, or floating point image. The only requirement is that it contain a closed isosurface that you will identify as the seed by setting the IsosurfaceValue parameter of the filter. For a binary image you will want to set your isosurface value halfway between your on and off values (i.e. for 0's and 1's, use an isosurface value of 0.5).
- The second input is the feature image. This is the image from which the speed function will be calculated. For most applications, this is the image that you want to segment. The desired isosurface in your seed image should lie within the region of your feature image that you are trying to segment.
- See SegmentationLevelSetImageFilter for more information on Inputs.
- OUTPUTS
- The filter outputs a single, scalar, real-valued image. Positive *values in the output image are inside the segmented region and negative *values in the image are outside of the inside region. The zero crossings of *the image correspond to the position of the level set front.
- See SparseFieldLevelSetImageFilter and SegmentationLevelSetImageFilter for more information.
- PARAMETERS
- There are five parameters important for controlling the behavior of this filter.
- (1) Threshold. Sets the thresholding value of the Canny edge detection. See CannyEdgeDetectionImageFilter for more information.
- (2) Variance. Controls the smoothing parameter of the gaussian filtering done during Canny edge detection.
- (3) CurvatureScaling. Controls the degree to which curvature influences the evolution of the level set. Higher values relative to Propagation and Advection scalings will yield a smoother surface.
- (4) PropagationScaling. Scales the propagation (speed) term of the level set equation. Set this term to zero to allow the level set to flow only down the gradient of the distance transform.
- (5) AdvectionScaling. Scales influence of the advection field relative to curvature and propagation terms.
- See also
- SegmentationLevelSetImageFilter
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CannySegmentationLevelSetFunction ,
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SparseFieldLevelSetImageFilter
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itk::simple::CannySegmentationLevelSet for the procedural interface
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itk::CannySegmentationLevelSetImageFilter for the Doxygen on the original ITK class.
Definition at line 115 of file sitkCannySegmentationLevelSetImageFilter.h.
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static bool | GetGlobalDefaultDebug () |
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static void | GlobalDefaultDebugOff () |
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static void | GlobalDefaultDebugOn () |
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static void | SetGlobalDefaultDebug (bool debugFlag) |
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static void | GlobalWarningDisplayOn () |
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static void | GlobalWarningDisplayOff () |
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static void | SetGlobalWarningDisplay (bool flag) |
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static bool | GetGlobalWarningDisplay () |
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static double | GetGlobalDefaultCoordinateTolerance () |
| Access the global tolerance to determine congruent spaces. More...
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static void | SetGlobalDefaultCoordinateTolerance (double) |
| Access the global tolerance to determine congruent spaces. More...
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static double | GetGlobalDefaultDirectionTolerance () |
| Access the global tolerance to determine congruent spaces. More...
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static void | SetGlobalDefaultDirectionTolerance (double) |
| Access the global tolerance to determine congruent spaces. More...
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static bool | SetGlobalDefaultThreader (const std::string &threader) |
| Set/Get the default threader used for process objects. More...
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static std::string | GetGlobalDefaultThreader () |
| Set/Get the default threader used for process objects. More...
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static void | SetGlobalDefaultNumberOfThreads (unsigned int n) |
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static unsigned int | GetGlobalDefaultNumberOfThreads () |
| Set/Get the default threader used for process objects. More...
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void | CheckImageMatchingDimension (const Image &image1, const Image &image2, const std::string &image2Name) |
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void | CheckImageMatchingPixelType (const Image &image1, const Image &image2, const std::string &image2Name) |
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void | CheckImageMatchingSize (const Image &image1, const Image &image2, const std::string &image2Name) |
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virtual unsigned long | AddITKObserver (const itk::EventObject &, itk::Command *) |
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virtual itk::ProcessObject * | GetActiveProcess () |
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virtual void | OnActiveProcessDelete () |
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virtual void | onCommandDelete (const itk::simple::Command *cmd) noexcept |
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virtual void | PreUpdate (itk::ProcessObject *p) |
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virtual void | RemoveITKObserver (EventCommand &e) |
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| NonCopyable ()=default |
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| NonCopyable (const NonCopyable &)=delete |
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NonCopyable & | operator= (const NonCopyable &)=delete |
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template<class TImageType > |
static void | FixNonZeroIndex (TImageType *img) |
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template<class TImageType > |
static TImageType::ConstPointer | CastImageToITK (const Image &img) |
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template<class TPixelType , unsigned int VImageDimension, unsigned int VLength, template< typename, unsigned int > class TVector> |
static Image | CastITKToImage (itk::Image< TVector< TPixelType, VLength >, VImageDimension > *img) |
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template<unsigned int VImageDimension, unsigned int VLength, template< unsigned int > class TVector> |
static Image | CastITKToImage (itk::Image< TVector< VLength >, VImageDimension > *img) |
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template<class TImageType > |
static Image | CastITKToImage (TImageType *img) |
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static const itk::EventObject & | GetITKEventObject (EventEnum e) |
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template<typename T > |
static std::ostream & | ToStringHelper (std::ostream &os, const T &v) |
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static std::ostream & | ToStringHelper (std::ostream &os, const char &v) |
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static std::ostream & | ToStringHelper (std::ostream &os, const signed char &v) |
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static std::ostream & | ToStringHelper (std::ostream &os, const unsigned char &v) |
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