Applying a SimpleFilter to a sequence

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1

I’m trying to apply a LaplacianSharpeningImageFilter to a volume sequence (4DCT) using the python interpreter. I’m used to using loadable modules via python but I understand that SimpleFilters is a scripted module. I’m trying to loop through the sequence and execute the filter widget on every image in the sequence.

The function that I’ve written does not seem to work as I’d thought and only the first image in the sequence is filtered. Am I missing something about how to execute a scripted module in a loop or the functionality of the applyButton call? I thought the issue might be due to the MRML scene changing to the output volume after executing the widget (b.click()), but I’ve added a call to a function that sets the MRML display back to the original sequence. Any advice or examples of applying a scripted module to a sequence would be appreciated.

def laplace_sharp_seq(seq_name, n_start, n_vol):

# define widget
filter_widget = slicer.modules.SimpleFiltersWidget
filter_params = filter_widget.filterParameters
filter_widget.filterSelector.setCurrentIndex(142) # Laplacian Filter
b = filter_widget.applyButton

# load sequence and sequence browser
seq = slicer.util.getNode(seq_name)
seq_browser = slicer.util.getNode(seq_name + " browser")


for node_id in range(n_start, n_vol + n_start):
    print(node_id)
    update_display(seq). # make sure the MRML scene is showing the sequence
    seq_browser.SetSelectedItemNumber(node_id)
    outModel=slicer.vtkMRMLScalarVolumeNode()
    outModel.SetName("test_py_"+str(node_id))
    slicer.mrmlScene.AddNode(outModel)
    filter_params.outputSelector.setCurrentNode(outModel)
    b.click() 
return
2

Simple Filters module runs the processing in the background. You need to check if processing is completed and only then switch to the next frame.

Instead of simulating button clicks it would be more robust to use Simple Filters logic, or go one level lower and use SimpleITK filters.

3

Great, thanks. I got the widget version to work and will try out a version using the logic.

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