Main Page   Class Hierarchy   Alphabetical List   Compound List   File List   Compound Members   File Members   Related Pages  

vtkImageBlend Class Reference

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

#include <vtkImageBlend.h>

Inheritance diagram for vtkImageBlend:

Inheritance graph
[legend]
Collaboration diagram for vtkImageBlend:

Collaboration graph
[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 SetBlendMode (int)
virtual int GetBlendMode ()
void SetBlendModeToNormal ()
void SetBlendModeToCompound ()
const char * GetBlendModeAsString (void)
virtual void SetCompoundThreshold (float)
virtual float GetCompoundThreshold ()
virtual void UpdateData (vtkDataObject *output)

Static Public Methods

vtkImageBlend * New ()
int IsTypeOf (const char *type)
vtkImageBlend * SafeDownCast (vtkObject *o)

Protected Methods

 vtkImageBlend ()
 ~vtkImageBlend ()
 vtkImageBlend (const vtkImageBlend &)
void operator= (const vtkImageBlend &)
void ComputeInputUpdateExtent (int inExt[6], int outExt[6], int whichInput)
void ThreadedExecute (vtkImageData **inDatas, vtkImageData *outData, int extent[6], int id)

Protected Attributes

double * Opacity
int OpacityArrayLength
int BlendMode
float CompoundThreshold

Detailed Description

blend images together using alpha or opacity.

Date:
2000/12/10 20:09:03
Revision:
1.10
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. Different blending modes are available:

Normal (default) : The blending rules are very similar to those for VTK texture maps. The alpha value of the first input, if present, is 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 <- 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
 }
Examples:
vtkImageBlend (examples)

Definition at line 105 of file vtkImageBlend.h.


Constructor & Destructor Documentation

vtkImageBlend::vtkImageBlend   [protected]
 

vtkImageBlend::~vtkImageBlend   [protected]
 

vtkImageBlend::vtkImageBlend const vtkImageBlend &    [inline, protected]
 

Definition at line 138 of file vtkImageBlend.h.


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
 

virtual void vtkImageBlend::SetBlendMode int    [virtual]
 

Set the blend mode

virtual int vtkImageBlend::GetBlendMode   [virtual]
 

void vtkImageBlend::SetBlendModeToNormal   [inline]
 

Definition at line 122 of file vtkImageBlend.h.

void vtkImageBlend::SetBlendModeToCompound   [inline]
 

Definition at line 124 of file vtkImageBlend.h.

const char * vtkImageBlend::GetBlendModeAsString void    [inline]
 

Get the blending mode as a descriptive string

Definition at line 156 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]
 

virtual void vtkImageBlend::UpdateData vtkDataObject   output [virtual]
 

Reimplemented from vtkSource.

void vtkImageBlend::operator= const vtkImageBlend &    [inline, protected]
 

Definition at line 139 of file vtkImageBlend.h.

void vtkImageBlend::ComputeInputUpdateExtent int    inExt[6],
int    outExt[6],
int    whichInput
[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.


Member Data Documentation

double* vtkImageBlend::Opacity [protected]
 

Definition at line 149 of file vtkImageBlend.h.

int vtkImageBlend::OpacityArrayLength [protected]
 

Definition at line 150 of file vtkImageBlend.h.

int vtkImageBlend::BlendMode [protected]
 

Definition at line 151 of file vtkImageBlend.h.

float vtkImageBlend::CompoundThreshold [protected]
 

Definition at line 152 of file vtkImageBlend.h.


The documentation for this class was generated from the following file:
Generated on Wed Nov 21 12:48:17 2001 for VTK by doxygen1.2.11.1 written by Dimitri van Heesch, © 1997-2001