[vtk-developers] RGBA to RGB

[Andreas Gamber]

Hello everyone,

does anyone know a possibility to convert RGBA-vtkImageData to RGB-vtkImageData?

I have to connect an OpenGL-application with a VTK-client. 


On OpenGL-side:
unsigned char pdata = new unsigned char[width*height*4];
glReadPixels(0,0,width,height,GL_RGBA,GL_UNSIGNED_BYTE,pdata);

The pdata-array holds the pixel-data as RGBA.



The VTK-application-side:
vtkImageImport *imageImport = vtkImageImport::New();
    imageImport->SetNumberOfScalarComponents(4);
    imageImport->SetWholeExtent(0,width-1,0,height-1,0,0);
    imageImport->SetDataExtentToWholeExtent();
    imageImport->SetDataScalarTypeToUnsignedChar();
    imageImport->SetImportVoidPointer(pdata);


imageImport->GetOutput() delivers RGBA-vtkImageData but the VTK-client is only able to handle RGB vtkImageData. 

The client-application is supposed to work in real time, so a simple reorganisation of the data-array
is impossible because it takes to much time.

Does VTK provide a method to get rid of the Alpha-part?


Thanks,
Andreas
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