Calling ImageJ Image Calculator operations from Python script

I am trying to add some ImageJ processing to a python script. For starters, e.g. pixel-wise multiplication of two images (Image Calculator, Multiply). I can multiply two arrays: imgr = ij.op().run('math.multiply', ij.py.to_java(imgA), ij.py.to_java(imgB)), but that seems to be matrix-multiplication.

Does anyone know about some documentation (apart of the official Jupyter notebook, which does not seem to be too helpful to me), or at least some working code examples, which would call ImageJ from a Python script?