vtkImageBlend Class Reference

#include <vtkImageBlend.h>

Inheritance diagram for vtkImageBlend:

[legend]

Collaboration diagram for vtkImageBlend:

[legend]

List of all members.

Detailed Description

blend images together using alpha or opacity

vtkImageBlend takes L, LA, RGB, or RGBA images as input and blends them according to the alpha values and/or the opacity setting for each input.

The spacing, origin, extent, and number of components of the output are the same as those for the first input. If the input has an alpha component, then this component is copied unchanged into the output. In addition, if the first input has either one component or two components i.e. if it is either L (greyscale) or LA (greyscale + alpha) then all other inputs must also be L or LA.

Different blending modes are available:

Normal (default) : This is the standard blending mode used by OpenGL and other graphics packages. The output always has the same number of components and the same extent as the first input. The alpha value of the first input is not used in the blending computation, instead it is copied directly to the output.

 output <- input[0]
 foreach input i {
   foreach pixel px {
     r <- input[i](px)(alpha) * opacity[i]
     f <- (255 - r)
     output(px) <- output(px) * f + input(px) * r
   }
 }

Compound : Images are compounded together and each component is scaled by the sum of the alpha/opacity values. Use the CompoundThreshold method to set specify a threshold in compound mode. Pixels with opacity*alpha less or equal than this threshold are ignored. The alpha value of the first input, if present, is NOT copied to the alpha value of the output. The output always has the same number of components and the same extent as the first input.

 output <- 0
 foreach pixel px {
   sum <- 0
   foreach input i {
     r <- input[i](px)(alpha) * opacity(i)
     sum <- sum + r
     if r > threshold {
       output(px) <- output(px) + input(px) * r
     }
   }
   output(px) <- output(px) / sum
 }

Tests:: vtkImageBlend (Tests)

Definition at line 87 of file vtkImageBlend.h.


Public Types
typedef vtkThreadedImageAlgorithm	Superclass
Public Member Functions
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)
virtual void	ReplaceNthInputConnection (int idx, vtkAlgorithmOutput *input)
int	GetNumberOfInputs ()

void	SetInput (int num, vtkDataObject *input)
void	SetInput (vtkDataObject *input)

vtkDataObject *	GetInput (int num)
vtkDataObject *	GetInput ()

void	SetOpacity (int idx, double opacity)
double	GetOpacity (int idx)

void	SetStencil (vtkImageStencilData *stencil)
vtkImageStencilData *	GetStencil ()

virtual void	SetBlendMode (int)
virtual int	GetBlendMode ()
void	SetBlendModeToNormal ()
void	SetBlendModeToCompound ()
const char *	GetBlendModeAsString (void)

virtual void	SetCompoundThreshold (double)
virtual double	GetCompoundThreshold ()
Static Public Member Functions
static vtkImageBlend *	New ()
static int	IsTypeOf (const char *type)
static vtkImageBlend *	SafeDownCast (vtkObject *o)
Protected Member Functions
	vtkImageBlend ()
	~vtkImageBlend ()
virtual int	RequestUpdateExtent (vtkInformation , vtkInformationVector , vtkInformationVector )
void	InternalComputeInputUpdateExtent (int inExt[6], int outExt[6], int inWExtent[6])
void	ThreadedRequestData (vtkInformation request, vtkInformationVector inputVector, vtkInformationVector outputVector, vtkImageData *inData, vtkImageData outData, int ext[6], int id)
virtual int	FillInputPortInformation (int, vtkInformation *)
virtual int	RequestData (vtkInformation request, vtkInformationVector inputVector, vtkInformationVector outputVector)
Protected Attributes
double *	Opacity
int	OpacityArrayLength
int	BlendMode
double	CompoundThreshold
int	DataWasPassed

Member Typedef Documentation

typedef vtkThreadedImageAlgorithm vtkImageBlend::Superclass

Reimplemented from vtkThreadedImageAlgorithm.

Definition at line 91 of file vtkImageBlend.h.

Constructor & Destructor Documentation

vtkImageBlend::vtkImageBlend ( ) [protected]

vtkImageBlend::~vtkImageBlend ( ) [protected]

Member Function Documentation

static vtkImageBlend* vtkImageBlend::New ( ) [static]

Create an object with Debug turned off, modified time initialized to zero, and reference counting on.

Reimplemented from vtkAlgorithm.

virtual const char* vtkImageBlend::GetClassName ( ) [virtual]

Reimplemented from vtkThreadedImageAlgorithm.

static int vtkImageBlend::IsTypeOf ( const char * name ) [static]

Return 1 if this class type is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkThreadedImageAlgorithm.

virtual int vtkImageBlend::IsA ( const char * name ) [virtual]

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkThreadedImageAlgorithm.

static vtkImageBlend* vtkImageBlend::SafeDownCast ( vtkObject * o ) [static]

Reimplemented from vtkThreadedImageAlgorithm.

void vtkImageBlend::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)			`[virtual]`

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkThreadedImageAlgorithm.

virtual void vtkImageBlend::ReplaceNthInputConnection	(	int	idx,
		vtkAlgorithmOutput *	input
	)			`[virtual]`

Replace one of the input connections with a new input. You can only replace input connections that you previously created with AddInputConnection() or, in the case of the first input, with SetInputConnection().

void vtkImageBlend::SetInput	(	int	num,
		vtkDataObject *	input
	)

Set an Input of this filter. This method is only for support of old-style pipeline connections. When writing new code you should use SetInputConnection(), AddInputConnection(), and ReplaceNthInputConnection() instead.

Reimplemented from vtkImageAlgorithm.

void vtkImageBlend::SetInput ( vtkDataObject * input ) [inline]

Set an Input of this filter. This method is only for support of old-style pipeline connections. When writing new code you should use SetInputConnection(), AddInputConnection(), and ReplaceNthInputConnection() instead.

Reimplemented from vtkImageAlgorithm.

Definition at line 106 of file vtkImageBlend.h.

vtkDataObject* vtkImageBlend::GetInput ( int num )

Get one input to this filter. This method is only for support of old-style pipeline connections. When writing new code you should use vtkAlgorithm::GetInputConnection(0, num).

Reimplemented from vtkImageAlgorithm.

vtkDataObject* vtkImageBlend::GetInput ( ) [inline]

Get one input to this filter. This method is only for support of old-style pipeline connections. When writing new code you should use vtkAlgorithm::GetInputConnection(0, num).

Reimplemented from vtkImageAlgorithm.

Definition at line 114 of file vtkImageBlend.h.

int vtkImageBlend::GetNumberOfInputs ( ) [inline]

Get the number of inputs to this filter. This method is only for support of old-style pipeline connections. When writing new code you should use vtkAlgorithm::GetNumberOfInputConnections(0).

Definition at line 120 of file vtkImageBlend.h.

void vtkImageBlend::SetOpacity	(	int	idx,
		double	opacity
	)

Set the opacity of an input image: the alpha values of the image are multiplied by the opacity. The opacity of image idx=0 is ignored.

double vtkImageBlend::GetOpacity ( int idx )

Set the opacity of an input image: the alpha values of the image are multiplied by the opacity. The opacity of image idx=0 is ignored.

void vtkImageBlend::SetStencil ( vtkImageStencilData * stencil )

Set a stencil to apply when blending the data.

vtkImageStencilData* vtkImageBlend::GetStencil ( )

Set a stencil to apply when blending the data.

virtual void vtkImageBlend::SetBlendMode ( int ) [virtual]

Set the blend mode

virtual int vtkImageBlend::GetBlendMode ( ) [virtual]

Set the blend mode

void vtkImageBlend::SetBlendModeToNormal ( ) [inline]

Set the blend mode

Definition at line 141 of file vtkImageBlend.h.

void vtkImageBlend::SetBlendModeToCompound ( ) [inline]

Set the blend mode

Definition at line 143 of file vtkImageBlend.h.

const char * vtkImageBlend::GetBlendModeAsString ( void ) [inline]

Get the blending mode as a descriptive string

Definition at line 193 of file vtkImageBlend.h.

virtual void vtkImageBlend::SetCompoundThreshold ( double ) [virtual]

Specify a threshold in compound mode. Pixels with opacity*alpha less or equal the threshold are ignored.

virtual double vtkImageBlend::GetCompoundThreshold ( ) [virtual]

Specify a threshold in compound mode. Pixels with opacity*alpha less or equal the threshold are ignored.

virtual int vtkImageBlend::RequestUpdateExtent	(	vtkInformation *	,
		vtkInformationVector **	,
		vtkInformationVector *
	)			`[protected, virtual]`

Reimplemented from vtkImageAlgorithm.

void vtkImageBlend::InternalComputeInputUpdateExtent	(	int	inExt[6],
		int	outExt[6],
		int	inWExtent[6]
	)			`[protected]`

void vtkImageBlend::ThreadedRequestData	(	vtkInformation *	request,
		vtkInformationVector **	inputVector,
		vtkInformationVector *	outputVector,
		vtkImageData ***	inData,
		vtkImageData **	outData,
		int	extent[6],
		int	threadId
	)			`[protected, virtual]`

If the subclass does not define an Execute method, then the task will be broken up, multiple threads will be spawned, and each thread will call this method. It is public so that the thread functions can call this method.

Reimplemented from vtkThreadedImageAlgorithm.

virtual int vtkImageBlend::FillInputPortInformation	(	int	port,
		vtkInformation *	info
	)			`[protected, virtual]`

Fill the input port information objects for this algorithm. This is invoked by the first call to GetInputPortInformation for each port so subclasses can specify what they can handle.

Reimplemented from vtkImageAlgorithm.

virtual int vtkImageBlend::RequestData	(	vtkInformation *	request,
		vtkInformationVector **	inputVector,
		vtkInformationVector *	outputVector
	)			`[protected, virtual]`