How can I access data from renderWindow?

[Tesla2678]

Hello There,

I want to make the slicer showed in the “Red” widget curve.
From

To

In order to do this, I am trying to get slice data before it was rendered.
I have no idea how to do this, I can only get the “renderWindow” from each “sliceView”.
How can I access the slice data and process it?

renWin=slicer.app.layoutManager().sliceWidget(“Red”).sliceView().renderWindow()

render=renWin.GetRenderers().GetFirstRenderer()