Silent crash when passing numpy array into mlab.run_func #250

I am trying to run the following function from a python script:
results = mlab.run_func('imTransform.m', {'arg1': curImage, 'arg2':1, 'arg3': 0.8, 'arg4': 0.5})

where curImage is a 2D numpy array.
But when I try to print out results['result'], then nothing is printed out and results['success'] prints out failed.
How do I pass numpy arrays into matlab?
Thanks!