lsseg::ChanVeseForce Class Reference

This ForceGenerator creates a normal force field, that leads to a segmentation similar to the model proposed by Chan and Vese. More...

#include <ChanVeseForce.h>

Inheritance diagram for lsseg::ChanVeseForce:

List of all members.


Public Member Functions
	ChanVeseForce (const Image< double > *img)
	Constructor, taking a pointer to the image to be segmented.
virtual	~ChanVeseForce ()
virtual void	init (const Image< double > img, const Mask mask)
	Initialize the ForceGenerator.
virtual void	update (const LevelSetFunction &phi)
	Update the force field based on a given segmentation of an image.
virtual void	force (LevelSetFunction &phi, const Mask *mask=0) const
	Get the complete normal force field as a LevelSetFunction.
virtual double	force3D (int x, int y, int z) const
	Get the normal force value of a (x, y, z) location in the current normal force field.
virtual double	force2D (int x, int y) const
	Get the normal force value of a (x, y) location in the current normal force field.
virtual double	force (size_t ix) const
	Get the normal force value of a particular pixel, specified by its internal storage index.
Private Attributes
double	mu_inside_
	average pixel value inside the Image's closed region, for the last segmentation
double	mu_outside_
	average pixel value inside the Image's open region, for the last segmentation
const Image< double > *const	img_
	pointer to the image to be segmented; specified in the constructor

Detailed Description

This ForceGenerator creates a normal force field, that leads to a segmentation similar to the model proposed by Chan and Vese.

This model seeks to minimize the Mumford-Shah functional by splitting the image into two regions where the pixel distribution is modeled by constant values for each region. It can be seen as the simplest model (in our setting, at least) that use a statistical model to describe each region. (The statistical model being, in our case, the average pixel value in each region). The relevant papers are [Chan99] and [Chan01]. Thomas Brox also gives a nice overview of this and other methods in [Brox05].

Definition at line 73 of file ChanVeseForce.h.

Constructor & Destructor Documentation

lsseg::ChanVeseForce::ChanVeseForce ( const Image< double > * img ) [inline]

Constructor, taking a pointer to the image to be segmented.

Definition at line 78 of file ChanVeseForce.h.

virtual lsseg::ChanVeseForce::~ChanVeseForce ( ) [inline, virtual]

Definition at line 83 of file ChanVeseForce.h.

Member Function Documentation

virtual double lsseg::ChanVeseForce::force ( size_t ix ) const [inline, virtual]

Get the normal force value of a particular pixel, specified by its internal storage index.

The internal storage index of any pixel can be found by applying the Image::indexOf() member function.

Implements lsseg::ForceGenerator.

Definition at line 158 of file ChanVeseForce.h.

virtual void lsseg::ChanVeseForce::force	(	LevelSetFunction &	phi,
		const Mask *	mask = `0`
	)			const `[inline, virtual]`

Get the complete normal force field as a LevelSetFunction.

Return values:

phi

the LevelSetFunction which will, upon completion of the function, contain the force field currently contained in the ForceGenerator

Parameters:

mask

(pointer to) an optional Mask that specifies which part(s) of the force field are active. (The inactive parts will not be filled into the LevelSetFunction $\phi$ ). If this pointer is left at zero, the whole of the force field is considered to be active.

Implements lsseg::ForceGenerator.

Definition at line 115 of file ChanVeseForce.h.

virtual double lsseg::ChanVeseForce::force2D	(	int	x,
		int	y
	)			const `[inline, virtual]`

Get the normal force value of a (x, y) location in the current normal force field.

Note:: for 3D images, z is here set to be 0. The method is not overloaded due to performance reasons. For true 3D fields, use the force3D() function instead.

Implements lsseg::ForceGenerator.

Definition at line 152 of file ChanVeseForce.h.

virtual double lsseg::ChanVeseForce::force3D	(	int	x,
		int	y,
		int	z
	)			const `[inline, virtual]`

Get the normal force value of a (x, y, z) location in the current normal force field.

Note:: The method is not overloaded due to performance reasons. If you want to get the normal force at a point in a 2D field, consider using the force2D() function instead, as this might be less expensive.

Implements lsseg::ForceGenerator.

Definition at line 146 of file ChanVeseForce.h.

virtual void lsseg::ChanVeseForce::init	(	const Image< double > *	img,
		const Mask *	mask
	)			`[inline, virtual]`

Initialize the ForceGenerator.

Parameters:

	img	(pointer to) the image that the ForceGenerator should use to derive the force field (i.e. the Image to be segmented).
	mask	(pointer to) an optional Mask that specifies which part(s) of the image are active. (No forces will be computed for the inactive part(s) of an image). If this pointer is left at zero, the whole of `img` is considered to be active.

Implements lsseg::ForceGenerator.

Definition at line 85 of file ChanVeseForce.h.

virtual void lsseg::ChanVeseForce::update ( const LevelSetFunction & phi ) [inline, virtual]

Update the force field based on a given segmentation of an image.

Parameters:

phi

this LevelSetFunction should be of the same shape as the Image that the ForceGenerator derives the force field from, and it specifies a segmentation of the Image. Taking this segmentation of the Image into consideration, the ForceGenerator computes the new force field.

Implements lsseg::ForceGenerator.

Definition at line 91 of file ChanVeseForce.h.