[vtkusers] Adding image writer to the pipeline gets itk reader fails

[Marcos]

Hi,

I wonder if somebody could help me, I'm stuck with this. Sorry if this was
asked before, I didn't find anything similar.

I got a simple pipeline working, starting with a itk::ImageFileReader who
connects to a vtkImageImport, passing through a vtkImageViewer and ending
in a QVTKWidget.

Great. I see an image in my QVTKWidget.

Now, writing to a file. Let's say a JPEG file.

I tried with a vtkWindowToImageFilter and a vtkJPEGWriter.

And that's where the weird things take place: the itk::ImageFileReader
fails trying to read the file; a segmentation fault in the Update() method.

Why? It's the same file, and the new code is added after.

I guess it is related to the pipeline, but I don't get how the end of
pipeline affects the beginning. Well, I know the Update method from the
first object could update the whole pipeline.

So I tried isolating the last part in a method, which is called from a menu
option: in my application, I "open" the file. I see a image in my viewer.
Then, later, I choose to export the image I see to a file. It's not until
that moment that I create the vtkWindowToImageFilter and vtkJPEGWriter
objects.

But itk::ImageFileReader fails again. If I comment the last lines, it works
again.

Here is the code, simplified (reader is a global variable: when I call
connectVTKWidget, it has called successfully (before I added the writing
part) the Update method and I can see a image in the widget):

void DCMBase::connectVTKWidget(QVTKWidget* widget)
{
    typedef itk::Image< signed short, 2 > TipoImagen;
    typedef itk::ImageFileReader< TipoImagen > Tiporeader;
    Tiporeader::Pointer reader;

    typedef itk::VTKImageExport< TipoImagen > TipoImagenExport;
    TipoImagenExport::Pointer exporter = TipoImagenExport::New();
    exporter->SetInput(reader->GetOutput());

    vtkImageImport *imageImport = vtkImageImport::New();
    this->ConnectPipelines(exporter, imageImport);

    vtkImageViewer* imageViewer = vtkImageViewer::New();
    imageViewer->SetInputConnection(imageImport->GetOutputPort());
    widget->SetRenderWindow(imageViewer->GetRenderWindow());

    // with this, itk::ImageFileReader fails!
    vtkWindowToImageFilter* filtroAImagen = vtkWindowToImageFilter::New();
    filtroAImagen->SetInput(widget->GetRenderWindow());
    vtkJPEGWriter* writer = vtkJPEGWriter::New();
    writer->SetFileName("myfile.jpg");
    //    writer->SetInputConnection(alg->GetOutputPort());

    try
    {
        writer->Update();
    }
    catch (itk::ExceptionObject& e)
    {
        std::cerr << "Excepción en escritura:" <<std::endl;
        std::cerr << e << std::endl;
    }

    imageViewer->Render();
}



Am I missing something? Thanks in advance.
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