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vtkImageBlend Class Reference

blend images together using alpha or opacity. More...

#include <vtkImageBlend.h>

Inheritance diagram for vtkImageBlend:

[legend]Collaboration diagram for vtkImageBlend:

[legend]List of all members.

Public Methods
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)
void	SetOpacity (int idx, double opacity)
double	GetOpacity (int idx)
virtual void	SetStencil (vtkImageStencilData *)
virtual vtkImageStencilData *	GetStencil ()
virtual void	SetBlendMode (int)
virtual int	GetBlendMode ()
void	SetBlendModeToNormal ()
void	SetBlendModeToCompound ()
const char *	GetBlendModeAsString (void)
virtual void	SetCompoundThreshold (float)
virtual float	GetCompoundThreshold ()
Static Public Methods
vtkImageBlend *	New ()
int	IsTypeOf (const char *type)
vtkImageBlend *	SafeDownCast (vtkObject *o)
Protected Methods
	vtkImageBlend ()
	~vtkImageBlend ()
void	ComputeInputUpdateExtent (int inExt[6], int outExt[6], int whichInput)
void	ExecuteInformation ()
void	ExecuteInformation (vtkImageData **, vtkImageData *)
void	ThreadedExecute (vtkImageData **inDatas, vtkImageData *outData, int extent[6], int id)
void	ExecuteData (vtkDataObject *output)
Protected Attributes
vtkImageStencilData *	Stencil
double *	Opacity
int	OpacityArrayLength
int	BlendMode
float	CompoundThreshold
int	DataWasPassed

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Detailed Description

blend images together using alpha or opacity.

Date:

2001/11/27 20:39:27

Revision:

1.17

Thanks:

Thanks to David G. Gobbi and Sebastien Barre who developed this class.

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 115 of file vtkImageBlend.h.

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Constructor & Destructor Documentation

vtkImageBlend::vtkImageBlend (    )  [protected]

vtkImageBlend::~vtkImageBlend (    )  [protected]

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Member Function Documentation

vtkImageBlend* vtkImageBlend::New (    )  [static]

Instantiate object with no start, end, or progress methods. Reimplemented from vtkImageMultipleInputFilter.

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

Return the class name as a string. This method is defined in all subclasses of vtkObject with the vtkTypeMacro found in vtkSetGet.h. Reimplemented from vtkImageMultipleInputFilter.

int vtkImageBlend::IsTypeOf (  const char *    type )  [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 vtkImageMultipleInputFilter.

virtual int vtkImageBlend::IsA (  const char *    type )  [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 vtkImageMultipleInputFilter.

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

Will cast the supplied object to vtkObject* is this is a safe operation (i.e., a safe downcast); otherwise NULL is returned. This method is defined in all subclasses of vtkObject with the vtkTypeMacro found in vtkSetGet.h. Reimplemented from vtkImageMultipleInputFilter.

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 vtkImageMultipleInputFilter.

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.

virtual void vtkImageBlend::SetStencil (  vtkImageStencilData *    )  [virtual]

Set a stencil to apply when blending the data.

virtual vtkImageStencilData* vtkImageBlend::GetStencil (    )  [virtual]

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 186 of file vtkImageBlend.h.

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

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

virtual float vtkImageBlend::GetCompoundThreshold (    )  [virtual]

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

void vtkImageBlend::ComputeInputUpdateExtent (  int    inExt[6], int    outExt[6], int    whichInput )  [protected, virtual]

Reimplemented from vtkImageMultipleInputFilter.

void vtkImageBlend::ExecuteInformation (    )  [inline, protected, virtual]

Reimplemented from vtkImageMultipleInputFilter. Definition at line 162 of file vtkImageBlend.h.

void vtkImageBlend::ExecuteInformation (  vtkImageData **    inputs, vtkImageData *    output )  [protected, virtual]

Reimplemented from vtkImageMultipleInputFilter.

void vtkImageBlend::ThreadedExecute (  vtkImageData **    inDatas, vtkImageData *    outData, int    extent[6], int    id )  [protected, virtual]

The execute method created by the subclass. This is kept public instead of protected since it is called from a non-member thread function. Reimplemented from vtkImageMultipleInputFilter.

void vtkImageBlend::ExecuteData (  vtkDataObject *    output )  [protected]

Reimplemented from vtkImageMultipleInputFilter.

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Member Data Documentation

vtkImageStencilData* vtkImageBlend::Stencil [protected]

Definition at line 174 of file vtkImageBlend.h.

double* vtkImageBlend::Opacity [protected]

Definition at line 175 of file vtkImageBlend.h.

int vtkImageBlend::OpacityArrayLength [protected]

Definition at line 176 of file vtkImageBlend.h.

int vtkImageBlend::BlendMode [protected]

Definition at line 177 of file vtkImageBlend.h.

float vtkImageBlend::CompoundThreshold [protected]

Definition at line 178 of file vtkImageBlend.h.

int vtkImageBlend::DataWasPassed [protected]

Definition at line 179 of file vtkImageBlend.h.

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The documentation for this class was generated from the following file:

• Imaging/vtkImageBlend.h

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