[vtkusers] creating images

[art langly]

Hello users,

I am using the vtkParallelManager interface (via vtkCompositeRenderManager) 
to create composite images....

What type of info does GetPixelData return? rgb array of size 
width*height*3?, rgba array of size width*height*4, or... ?

I have been assuming rgba, size width*height*4 and i am attempting to write 
images with a number of different vtkImageWriter conc. classes.. jpeg, bmp, 
pnm, png, tiff, and post script...

after acquiring the vtkUnsignedCharArray (I guess i can just check the size 
and number of components of this array to determine what was returned 
couldnt i???) either way, if it isnt 4 component data maybe thats my 
problem, otherwise...

i create an instance of vtkImageData...

      imageData->GetPointData()->SetScalars(dataArray);
      imageData->SetScalarType(VTK_UNSIGNED_CHAR);
      imageData->SetSpacing(1.,1.,1.); //?
      imageData->SetOrigin(0.,0.,0.); //?
      imageData->SetNumberOfScalarComponents(4);
      imageData->SetDimensions(width,height,1);

where dataArray was acquired through 
vtkCompositeRenderManager::GetPixelData...

this works fine w/ jpegs & bmp's, but not for pnm's, png's, tiffs, or post 
script (but the post script writer does not work w/ 4 component data)

any suggestions for what i am doing wrong? or.. what should i do in order to 
get any specific writer to work with the data returned from 
vtkCompositeRenderManager::GetPixelData?

Additionaly, I have a non-vtk composite function... it produces a 
width*height*4 size array of rgba values (transperency is not handled well, 
but the alpha values are there), I then create a vtkUnsignedCharArray w/ the 
c unsigned char array and procceed as I do when using the render manager, 
but the results are the same...

Thanks for your time
art langly

ps. im using mpi, the problems w/ the images seem to be independent if I 
handle mpi on my own or if i use vtkMPIController

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