SoGradientOperatorProcessing2d engine provides different algorithms to extract the edges of a 2D image. More...

#include <ImageViz/Engines/EdgeDetection/Gradient/SoGradientOperatorProcessing2d.h>

Inheritance diagram for SoGradientOperatorProcessing2d:

Public Types
enum	GradientOperator { CANNY_DERICHE = 0 , SHEN_CASTAN = 1 , CANNY = 3 , GAUSSIAN = 4 , SOBEL = 5 , PREWITT = 6 }

enum	GradientMode { AMPLITUDE_MAX_OF_MAGS = 0 , AMPLITUDE_EUCLIDEAN = 1 , AMPLITUDE_AND_ORIENTATION = 2 , X_AND_Y_GRADIENTS = 3 }

Public Types inherited from SoImageVizEngine
enum	ComputeMode { MODE_2D = 0 , MODE_3D = 1 , MODE_AUTO = 2 }
	Compute Mode This enum specifies whether the main input will be interpreted as a 3D volume or a stack of 2D images for processing. More...

enum	Neighborhood3d { CONNECTIVITY_6 = 0 , CONNECTIVITY_18 = 1 , CONNECTIVITY_26 = 2 }
	Neighborhood Connectivity 3D. More...

Public Member Functions
	SoGradientOperatorProcessing2d ()
	Constructor.

Public Member Functions inherited from SoImageVizEngine
virtual SoType	getTypeId () const
	Returns the type identifier for this specific instance.

virtual void	startEvaluate ()
	Evaluate engine and dependencies in another thread without blocking the current one.

virtual void	waitEvaluate ()
	Wait for the end of engine evaluation.

virtual void	abortEvaluate ()
	Abort current processing as soon as possible.

virtual bool	isEvaluating ()
	Returns true if the engine evaluation is in progress.

Public Member Functions inherited from SoEngine
virtual int	getOutputs (SoEngineOutputList &list) const
	Returns a list of outputs in this engine.

SoEngineOutput *	getOutput (const SbName &outputName) const
	Returns a reference to the engine output with the given name.

SbBool	getOutputName (const SoEngineOutput *output, SbName &outputName) const
	Returns (in outputName) the name of the engine output (output).

SoEngine *	copy () const
	Creates and returns an exact copy of the engine.

Public Member Functions inherited from SoFieldContainer
void	setToDefaults ()
	Sets all fields in this object to their default values.

SbBool	hasDefaultValues () const
	Returns TRUE if all of the object's fields have their default values.

SbBool	fieldsAreEqual (const SoFieldContainer *fc) const
	Returns TRUE if this object's fields are exactly equal to fc's fields.

void	copyFieldValues (const SoFieldContainer *fc, SbBool copyConnections=FALSE)
	Copies the contents of fc's fields into this object's fields.

SoNONUNICODE SbBool	set (const char *fieldDataString)
	Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.

SbBool	set (const SbString &fieldDataString)
	Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.

void	get (SbString &fieldDataString)
	Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string.

virtual int	getFields (SoFieldList &list) const
	Appends references to all of this object's fields to resultList, and returns the number of fields appended.

virtual int	getAllFields (SoFieldList &list) const
	Returns a list of fields, including the eventIn's and eventOut's.

virtual SoField *	getField (const SbName &fieldName) const
	Returns a the field of this object whose name is fieldName.

virtual SoField *	getEventIn (const SbName &fieldName) const
	Returns a the eventIn with the given name.

virtual SoField *	getEventOut (const SbName &fieldName) const
	Returns the eventOut with the given name.

SbBool	getFieldName (const SoField *field, SbName &fieldName) const
	Returns the name of the given field in the fieldName argument.

SbBool	enableNotify (SbBool flag)
	Notification at this Field Container is enabled (if flag == TRUE) or disabled (if flag == FALSE).

SbBool	isNotifyEnabled () const
	Notification is the process of telling interested objects that this object has changed.

virtual void	setUserData (void *data)
	Sets application data.

void *	getUserData (void) const
	Gets user application data.

Public Member Functions inherited from SoBase
virtual void	touch ()
	Marks an instance as modified, simulating a change to it.

virtual SbName	getName () const
	Returns the name of an instance.

virtual void	setName (const SbName &name)
	Sets the name of an instance.

void	setSynchronizable (const bool b)
	Sets this to be a ScaleViz synchronizable object.

bool	isSynchronizable () const
	Gets the ScaleViz synchronizable state of this object.

Public Member Functions inherited from SoRefCounter
void	ref () const
	Adds a reference to an instance.

void	unref () const
	Removes a reference from an instance.

void	unrefNoDelete () const
	unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero.

int	getRefCount () const
	Returns current reference count.

void	lock () const
	lock this instance.

void	unlock () const
	unlock this instance.

Public Member Functions inherited from SoTypedObject
SbBool	isOfType (const SoType &type) const
	Returns TRUE if this object is of the type specified in type or is derived from that type.

template<typename TypedObjectClass >
SbBool	isOfType () const
	Returns TRUE if this object is of the type of class TypedObjectClass or is derived from that class.

Public Attributes
SoSFImageDataAdapter	inImage
	The input image.

SoSFEnum	gradientOperator
	Select the gradient operator.

SoSFEnum	gradientMode
	Select an output mode.

SoSFFloat	standardDeviation
	The standard deviation.

SoImageVizEngineOutput< SoSFImageDataAdapter, SoImageDataAdapter * >	outGradientXImage
	The output X-gradient image.

SoImageVizEngineOutput< SoSFImageDataAdapter, SoImageDataAdapter * >	outGradientYImage
	The output Y-gradient image.

SoImageVizEngineOutput< SoSFImageDataAdapter, SoImageDataAdapter * >	outAmplitudeImage
	The output gradient amplitude image.

SoImageVizEngineOutput< SoSFImageDataAdapter, SoImageDataAdapter * >	outOrientationImage
	The output gradient orientation image.

Public Attributes inherited from SoImageVizEngine
SbEventHandler< EventArg & >	onBegin
	Event raised when the processing begins.

SbEventHandler< EventArg & >	onEnd
	Event raised when processing ends and the result is available.

SbEventHandler< EventArg & >	onProgress
	Event raised while processing is running.

Additional Inherited Members
Static Public Member Functions inherited from SoImageVizEngine
static SoType	getClassTypeId ()
	Returns the type identifier for this class.

Static Public Member Functions inherited from SoEngine
static SoType	getClassTypeId ()
	Returns the type identifier for the SoEngine class.

static SoEngine *	getByName (const SbName &name)
	Looks up engine(s) by name.

static int	getByName (const SbName &name, SoEngineList &list)
	Looks up engine(s) by name.

Static Public Member Functions inherited from SoFieldContainer
static SoType	getClassTypeId ()
	Returns the type of this class.

Static Public Member Functions inherited from SoBase
static SoType	getClassTypeId ()
	Returns type identifier for this class.

Static Public Member Functions inherited from SoTypedObject
static SoType	getClassTypeId ()
	Returns the type identifier for this class.

Detailed Description

SoGradientOperatorProcessing2d engine provides different algorithms to extract the edges of a 2D image.

For an introduction, see:

The SoGradientOperatorProcessing2d engine provides different algorithms to extract the edges of an image.

Note: You may normalize the filtered image, i.e. divide the output gray levels by the sum of absolute values of the kernel coefficients. If not, be aware that overflow may occur.

Canny-Deriche: It performs a recursive gradient computation to get the gradient in X and Y directions. It is an FIR (finite impulse response) filter. To minimize the effect of noise, it smooths the image before computing the gradient. A smoothing scale parameter determines the smoothing intensity. If the value is large, noise will be reduced but edges will be less sharp and only the most significant edges will survive. It is important to select the right coefficient to lower the noise just enough without defocusing the edges. Then it gets the maximum of these images with a gradient magnitude operation. For color images it calculates the maximum of intensity or the euclidian mean.
Shen-Castan: It calculates the gradient of Shen and Castan. It is a recursive and exponential filter that smooths an object and then extracts its edges. It is based on the Shen operator :

$f(x,y)=\frac{p^2}{4}\cdot e^{(-p(|x|+|y|))}$

The highest $p$ is, the more edges we get. For color images it calculates the maximum of intensity or the euclidian mean.

Canny: It performs an approximation to get the Canny-Deriche in X and Y directions using a convolution kernel 7x5 for X and 5x7 for Y. Result is nearly the same than Canny Deriche but process is much faster.
Gaussian: It performs a convolution with the derivatives of a Gaussian function along each image axis.
Sobel: It performs a convolution with the Sobel Kernel. $\mathbf{G_x} = \begin{bmatrix} -1 & 0 & +1 \\ -2 & 0 & +2 \\ -1 & 0 & +1 \end{bmatrix} \quad \mbox{and} \quad \mathbf{G_y} = \begin{bmatrix} -1 & -2 & -1 \\ 0 & 0 & 0 \\ +1 & +2 & +1 \end{bmatrix}$
Prewitt: It performs a convolution with the Prewitt Kernel. $\mathbf{G_x} = \begin{bmatrix} -1 & 0 & +1 \\ -1 & 0 & +1 \\ -1 & 0 & +1 \end{bmatrix} \quad \mbox{and} \quad \mathbf{G_y} = \begin{bmatrix} -1 & -1 & -1 \\ 0 & 0 & 0 \\ +1 & +1 & +1 \end{bmatrix}$

FILE FORMAT/DEFAULT

inImage	NULL
gradientOperator	CANNY_DERICHE
gradientMode	AMPLITUDE_MAX_OF_MAGS
standardDeviation	60.0f

Library references: gradient

Definition at line 130 of file SoGradientOperatorProcessing2d.h.

Member Enumeration Documentation

◆ GradientMode

enum SoGradientOperatorProcessing2d::GradientMode

Enumerator
AMPLITUDE_MAX_OF_MAGS	This option computes the gradient maximal amplitude. Only the outAmplitudeImage output is set using this mode.
AMPLITUDE_EUCLIDEAN	This option computes the gradient euclidean amplitude. Only the outAmplitudeImage output is set using this mode.
AMPLITUDE_AND_ORIENTATION	This option computes euclidean amplitude and the orientation (between -128 and +128 degrees). Both outAmplitudeImage and outOrientationImage outputs are set using this mode.
X_AND_Y_GRADIENTS	This option computes gradient in X and Y directions. Both outGradientXImage and outGradientYImage outputs are set using this mode.

Definition at line 190 of file SoGradientOperatorProcessing2d.h.

◆ GradientOperator

enum SoGradientOperatorProcessing2d::GradientOperator

Enumerator
CANNY_DERICHE	The gradient is computed using the Canny-Deriche algorithm. Supported gradient output modes : AMPLITUDE_MAX_OF_MAGS, AMPLITUDE_EUCLIDEAN, AMPLITUDE_AND_ORIENTATION and X_AND_Y_GRADIENTS.
SHEN_CASTAN	The gradient is computed using the Shen and Castan algorithm. Supported gradient output modes : AMPLITUDE_MAX_OF_MAGS.
CANNY	The gradient is computed using the Canny algorithm. Supported gradient output modes : AMPLITUDE_MAX_OF_MAGS and AMPLITUDE_EUCLIDEAN.
GAUSSIAN	The gradient is computed using the Gaussian algorithm. Supported gradient output modes : AMPLITUDE_MAX_OF_MAGS, AMPLITUDE_EUCLIDEAN, AMPLITUDE_AND_ORIENTATION and X_AND_Y_GRADIENTS.
SOBEL	The gradient is computed using the Sobel algorithm. Supported gradient output modes : AMPLITUDE_MAX_OF_MAGS, AMPLITUDE_EUCLIDEAN, AMPLITUDE_AND_ORIENTATION and X_AND_Y_GRADIENTS.
PREWITT	The gradient is computed using the Prewitt algorithm. Supported gradient output modes : AMPLITUDE_MAX_OF_MAGS, AMPLITUDE_EUCLIDEAN, AMPLITUDE_AND_ORIENTATION and X_AND_Y_GRADIENTS.